Renewable compositions

ABSTRACT

The present invention is directed to renewable compositions derived from fermentation of biomass, and integrated methods of preparing such compositions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser.No. 12/327,723, filed on Dec 3, 2008, now U.S. Pat. No.8,193,402 which claims priority to U.S. Provisional Appl. No.60/991,978, filed Dec. 3, 2007; U.S. Provisional Appl. No. 60/991,990,filed Dec. 3, 2007; U.S. Provisional Appl. No. 61/012,110, filed Dec. 7,2007; U.S. Provisional Appl. No. 61/035,076, filed Mar. 10, 2008; U.S.Provisional Appl. No. 61/038,980, filed Mar. 24, 2008; U.S. ProvisionalAppl. No. 61/039,153, filed Mar. 25, 2008; U.S. Provisional Appl. No.61/039,329, filed Mar. 25, 2008; U.S. Provisional Appl. No. 61/054,739,filed May 20, 2008; U.S. Provisional Appl. No. 61/054,752, filed May 20,2008; U.S. Provisional Appl. No. 61/055,600, filed May 23, 2008; U.S.Provisional Appl. No. 61/073,688, filed June 18, 2008; U.S. ProvisionalAppl. No. 61/083,044, filed Jul. 23, 2008; U.S. Provisional Appl. No.61/083,048, filed Jul. 23, 2008; and U.S. Provisional Appl. No.61/091,858, filed Aug. 26, 2008. Each of the above applications isherein incorporated by reference in its entirety for all purposes.

BACKGROUND OF THE INVENTION

Conventional transportation fuels and many fine chemicals (e.g.monomers, polymers, plasticizers, adhesives, thickeners, aromatic andaliphatic solvents, etc.) are typically derived from non-renewable rawmaterials such as petroleum. However, there is increasing concern thatthe use of petroleum as a basic raw material contributes toenvironmental degradation (e.g., global warming, air and waterpollution, etc.) and fosters overdependence on unreliable petroleumsupplies from politically unstable parts of the world.

For example, burning a gallon of typical gasoline produces over 19pounds of carbon dioxide. Because no carbon dioxide is consumed by arefinery in the manufacture of gasoline, the net carbon dioxide producedis always at least as great as the amount of carbon contained in thefuel. In addition, the net carbon dioxide produced by burning a gallonof petroleum-based gasoline can be even higher when the combustion ofadditional fossil fuels required to power the refinery and thetransportation vehicles that bring the fuel to market are considered. Incontrast to fossil fuels, when biomass is converted into biofuels,carbon dioxide is removed from the atmosphere. In contrast for a biofuelprocess, it is possible and probable that the net carbon dioxide ofburning a gallon of biofuel is less than the carbon dioxidecorresponding to the carbon atoms in the biofuel. Thus, a definingfeature of biofuels and biofuel blends is that the net carbon dioxideproduced by burning a gallon of biofuel or biofuel blend is less thanthe net carbon dioxide produced by burning a gallon of gasoline. Thus,biofuels and biomass-derived organic chemical materials providesignificant environmental benefits. There is thus a need to identify newrenewable sources of raw materials useful for e.g. transportation fuelsand as raw materials for the chemical industry, which are scalable andcost-competitive with conventional sources.

Market fluctuations in the 1970s, due to the Arab oil embargo and theIranian revolution, coupled with the decrease in US oil production ledto an increase in crude oil prices and a renewed interest in renewablematerials. Today, many interest groups including policy makers, industryplanners, aware citizens, and the financial community are interested inreplacing or supplementing petroleum-derived fuels with biomass-derivedbiofuels. One leading motivation for developing biofuels is economic,namely the concern that the consumption rate of crude oil may soonexceed the supply rate, thus leading to significantly increased fuelcost.

Biofuels are renewable transportation fuels which have a long historyranging back to the beginning on the 20th century. As early as 1900,Rudolf Diesel demonstrated an engine running on peanut oil. Soonthereafter, Henry Ford demonstrated his Model T running on ethanolderived from corn. However, petroleum-derived fuels displaced biofuelsin the 1930s and 1940s due to increased supply and efficiency at a lowercost.

At present, biofuels tend to be produced using local agriculturalresources in many relatively small facilities, and are viewed asproviding a stable and secure supply of fuels independent of thegeopolitical problems associated with petroleum. At the same time,biofuels can enhance the agricultural sector of national economies. Inaddition, environmental concerns relating to the possibility of carbondioxide related climate change is an important social and ethicaldriving force which is triggering new government regulations andpolicies such as caps on carbon dioxide emissions from automobiles,taxes on carbon dioxide emissions, and tax incentives for the use ofbiofuels.

The acceptance of biofuels depends primarily on their economicalcompetitiveness compared to petroleum-derived fuels. As long as biofuelsare more expensive than petroleum-derived fuels, the use of biofuelswill be limited to specialty applications and niche markets. Today, theprimary biofuels are ethanol and biodiesel. Ethanol is typically made bythe fermentation of corn in the US and from sugar cane in Brazil.Ethanol from corn or sugar cane is competitive with petroleum-derivedgasoline (exclusive of subsidies or tax benefits) when crude oil staysabove $50 per barrel and $40 per barrel, respectively. Biodiesel iscompetitive with petroleum-based diesel when the price of crude oil is$60/barrel or more.

In addition to cost, the acceptance of biofuels is predicated on theirperformance characteristics, their ability to run in many types ofexisting equipment, and their ability to meet demanding industryspecifications that have evolved over the last century. Fuel ethanol hasachieved only limited market penetration in the automotive market inpart due to its much lower energy content compared to gasoline, andother properties (such as water absorption) that hinder its adoption asa pure fuel. To date, the maximum percentage of ethanol used in gasolinehas been 85% (the E85 grade), and this has found use in only a smallfraction of newer, dual-fuel cars where the engines have been redesignedto accommodate the E85 fuel.

Acceptance of biofuels in the diesel industry and aviation industry haslagged even farther behind that of the automotive industry. Methyltrans-esterified fatty acids from seed oils (such as soybean, corn,etc.) have several specific disadvantages compared to petroleum-deriveddiesel fuels, particularly the fact that insufficient amounts of seedoil are available. Even under the most optimistic scenarios, seed oilscould account for no more than 5% of the overall diesel demand.Furthermore, for diesel and aviation engines, the cold flow propertiesof the long chain fatty esters from seed oils are sufficiently poor soas to cause serious operational problems even when used at levels as lowas 5%. Under cold conditions, the precipitation and crystallization offatty paraffin waxes can cause debilitating flow and filter pluggingproblems. For aviation engines, the high temperature instability of theesters and olefinic bonds in seed oils is also a potential problem. Touse fatty acid esters for jet fuel, the esters must be hydrotreated toremove all oxygen and olefinic bonds. Additionally, jet fuels mustcontain aromatics in order to meet the stringent energy density and sealswelling demands of jet turbine engines. Accordingly, synthetic jetfuels including hydrotreated fatty acid esters from seed oils, orsynthetic fuels produced from coal, must be blended with aromaticcompounds derived from fossil fuels to fully meet jet fuelspecifications.

Aromatic compounds are conventionally produced from petroleum feedstocksin refineries by reacting mixtures of light hydrocarbons (C₁-C₆) andnaphthas over various catalysts at high heat and pressure. The mixtureof light hydrocarbons available to a refinery is diverse, and provides amixture of aromatic compounds suitable for use in fuel once thecarcinogenic benzene is removed. Alternatively, the hydrocarbonfeedstocks can be purified into single components to produce a pureraromatic product. For example, aromatization of pure isoocteneselectively forms p-xylene over some catalysts. The by-products of thesereactions are very light fractions containing hydrogen, methane, ethane,and propane gases which are captured at the refinery for other uses.

Low molecular weight alkanes and alkenes can also be converted intoaromatic compounds such as xylene using a variety of alumina and silicabased catalysts and reactor configurations. For example, the Cyclarprocess developed by UOP and BP for converting liquefied petroleum gasinto aromatic compounds uses a gallium-doped zeolite (Appl. Catal. A,1992, 89, p. 1-30). Other catalysts reported in the patent literatureinclude bismuth, lead, or antimony oxides (U.S. Pat. Nos. 3,644,550 and3,830,866), chromium treated alumina (U.S. Pat. Nos. 3,836,603 and6,600,081 B2), rhenium treated alumina (U.S. Pat. No. 4,229,320) andplatinum treated zeolites (WO 2005/065393 A2).

Alternatively, low molecular weight (C₂-C₅) alkanes and alkenes can betreated with acidic catalysts to produce higher molecular weight(C₈-C₂₀) alkanes and alkenes. Mixtures of these alkanes and alkenes arethen blended at the refinery to provide gasoline, jet, and diesel fuel.In particular, these “alkylates” can be blended with gasoline to reducevapor pressure and raise octane value. However, unlike gasoline anddiesel, jet fuel specifications cannot tolerate high quantities ofolefins. To produce useful hydrocarbons suitable for jet fuel, theolefins must be reduced to saturated hydrocarbons using an additionalhydrogenation step. In general, in petroleum refineries small alkanesand alkenes have little value and are processed as described above toform higher molecular weight hydrocarbons that can be blended into thehigher value hydrocarbons that constitute the majority of a barrel ofcrude oil.

The compositions and processes of the present invention provideimproved, renewable biofuels with costs and performance propertiescomparable to, or superior to existing biofuels and petroleum-derivedfuels (e.g., jet fuels). In addition, the process of the presentinvention provides an integrated and simple method for producingsaturated C₈-C₂₄ aliphatic hydrocarbons and aromatics from renewablealcohols (with low levels of olefins) derived from biomass. In oneembodiment, the process of the present invention provides anon-specification fuel (e.g., gasoline, diesel, or jet fuel) which iscompletely comprised of renewable hydrocarbons.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is directed to a process forpreparing renewable hydrocarbons comprising:

-   -   (a) treating biomass to form a feedstock;    -   (b) fermenting the feedstock with one or more species of        microorganism, thereby forming one or more C₂-C₆ alcohols;    -   (c) dehydrating at least a portion of the one or more C₂-C₆        alcohols obtained in step (b), thereby forming a product        comprising one or more C₂-C₆ olefins;    -   (d) isolating the one or more C₂-C₆ olefins;    -   (e) oligomerizing at least a portion of the one or more C₂-C₆        olefins isolated in step (d), thereby forming a product        comprising one or more C₆-C₂₄ unsaturated oligomers; and    -   (f) optionally hydrogenating at least a portion of the product        of step (e) in the presence of hydrogen, thereby forming a        product comprising one or more C₆-C₂₄ saturated alkanes.

In another embodiment, the present invention is directed to a processfor preparing a renewable aromatic compound, comprising:

-   -   (i) treating biomass to form a feedstock;    -   (ii) fermenting the feedstock with one or more species of        microorganism, thereby forming one or more C₂-C₆ alcohols;    -   (iii) dehydrating at least a portion of the one or more C₂-C₆        alcohols obtained in step (ii), thereby forming a product        comprising one or more C₂-C₆ olefins;    -   (iv) isolating the one or more C₂-C₆ olefins;    -   (v) optionally oligomerizing the one or more C₂-C₆ olefins to        one or more dimers and/or one or more trimers of the C₂-C₆        olefins;    -   (vi) aromatizing one or more C₂-C₆ olefins from step (iv) or one        or more dimers and/or one or more trimers of the C₂-C₆ olefins        of step (v), thereby forming a product comprising C₆-C₁₄        aromatic hydrocarbons, and hydrogen; and    -   (vii) optionally oligomerizing the product of step (vi) in the        presence of the one or more C₂-C₆ olefins of step (v) to form a        product comprising one or more C₈-C₁₆ aromatic hydrocarbons.

In still another embodiment, the present invention is directed to aprocess for preparing renewable oxidized hydrocarbons comprising:

-   -   (A) treating biomass to form a feedstock;    -   (B) fermenting the feedstock with one or more species of        microorganism, thereby forming one or more C₂-C₆ alcohols;    -   (C) dehydrating at least a portion of the one or more C₂-C₆        alcohols obtained in step (b), thereby forming a product        comprising one or more C₂-C₆ olefins;    -   (D) isolating the one or more C₂-C₆ olefins; and    -   (E) oxidizing the one or more C₂-C₆ olefins of step (c) to form        at least one oxidized hydrocarbon.

In still yet another embodiment, the present invention is directed to abiofuel or biofuel precursor prepared by the processes of the presentinvention described herein.

In further embodiments, the present invention is directed to a biofuelor biofuel precursor comprising at least 10% renewable C₈-C₂₄ branchedaliphatic hydrocarbons.

In still other embodiments, the present invention is directed to arenewable jet fuel, a renewable gasoline, a renewable aviation gasoline,a renewable diesel fuel, and renewable oxidized hydrocarbons.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of one embodiment of an integratedprocess for producing a renewable jet fuel from biomass.

FIG. 2 is a schematic diagram of a combined oligomerization and aromaticalkylation in one pot.

FIG. 3 is a comparison of GC traces of petroleum-derived gasoline and GCtraces of a renewable gasoline prepared by the process of the presentinvention.

FIG. 4 is a comparison of GC traces of petroleum-derived jet fuel and GCtraces of a renewable jet fuel prepared by the process of the presentinvention.

FIG. 5 is a comparison of GC traces of petroleum-derived aviationgasoline and GC traces of a renewable aviation gasoline prepared by theprocess of the present invention.

FIG. 6 is a comparison of GC traces of petroleum-derived diesel fuel andGC traces of a renewable diesel fuel prepared by the process of thepresent invention.

FIG. 7 is a Table comparing various properties of petroleum-deriveddiesel fuel and a renewable diesel fuel prepared by the process of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

All documents disclosed herein (including patents, journal references,ASTM methods, etc.) are each incorporated by reference in their entiretyfor all purposes.

The term “biocatalyst” means a living system or cell of any type thatspeeds up chemical reactions by lowering the activation energy of thereaction and is neither consumed nor altered in the process.Biocatalysts may include, but are not limited to, microorganisms such asyeasts, fungi, bacteria, and archaea.

The biocatalyst herein disclosed can convert various carbon sources intobiofuels. The term “carbon source” generally refers to a substancesuitable to be used as a source of carbon for prokaryotic or eukaryoticcell growth. Carbon sources include, but are not limited to biomasshydrolysates, starch, sucrose, cellulose, hemicellulose, xylose, andlignin, as well as monomeric components of these substrates. Carbonsources can comprise various organic compounds in various formsincluding, but not limited to, polymers, carbohydrates, acids, alcohols,aldehydes, ketones, amino acids, peptides, etc. These include, forexample, various monosaccharides such as glucose, dextrose (D-glucose),maltose, oligosaccharides, polysaccharides, saturated or unsaturatedfatty acids, succinate, lactate, acetate, ethanol, etc., or mixturesthereof. Photosynthetic organisms can additionally produce a carbonsource as a product of photosynthesis. In some embodiments, carbonsources may be selected from biomass hydrolysates and glucose.

The term “feedstock” is defined as a raw material or mixture of rawmaterials supplied to a biocatalyst (e.g., microorganism) orfermentation process from which other products can be made. For example,a carbon source, such as biomass or the carbon compounds derived frombiomass (e.g., a biomass hydrolysate as described herein) are afeedstock for a biocatalyst (e.g., a microorganism) that produces abiofuel (e.g., ethanol, isobutanol) or biofuel precursor (e.g.,isobutanol) in a fermentation process. However, a feedstock may containnutrients other than a carbon source. The term feedstock is usedinterchangeably with the term “renewable feedstock”, as the feedstocksused are generated from biomass or traditional carbohydrates, which arerenewable substances.

The term “traditional carbohydrates” refers to sugars and starchesgenerated from specialized plants, such as sugar cane, corn, and wheat.Frequently, these specialized plants concentrate sugars and starches inportions of the plant, such as grains, that are harvested and processedto extract the sugars and starches. Traditional carbohydrates are usedas food, and also to a lesser extent, as renewable feedstocks forfermentation processes to generate biofuel precursors.

The term “biomass” as used herein refers primarily to the stems, leaves,and starch -containing portions of green plants, and is mainly comprisedof starch, lignin, cellulose, hemicellulose, and/or pectin. Biomass canbe decomposed by either chemical or enzymatic treatment to the monomericsugars and phenols of which it is composed (Wyman, C. E. 2003Biotechnological Progress 19:254-62). This resulting material, calledbiomass hydrolysate, is neutralized and treated to remove trace amountsof organic material that may adversely affect the biocatalyst, and isthen used as a feedstock for fermentations using a biocatalyst.Alternatively, the biomass may be thermochemically treated to producealcohols and alkanes that may be further treated to produce biofuels.

The term “starch” as used herein refers to a polymer of glucose readilyhydrolyzed by digestive enzymes. Starch is usually concentrated inspecialized portions of plants, such as potatoes, corn kernels, ricegrains, wheat grains, and sugar cane stems.

The term “lignin” as used herein refers to a polymer material, mainlycomposed of linked phenolic monomeric compounds, such as p-coumarylalcohol, coniferyl alcohol, and sinapyl alcohol, which forms the basisof structural rigidity in plants and is frequently referred to as thewoody portion of plants. Lignin is also considered to be thenon-carbohydrate portion of the cell wall of plants.

The team “cellulose” as used herein refers is a long-chain polymerpolysaccharide carbohydrate comprised of β-glucose monomer units, offormula (C₆H₁₀O₅)_(n), usually found in plant cell walls in combinationwith lignin and any hemicellulose.

The term “hemicellulose” refers to a class of plant cell-wallpolysaccharides that can be any of several heteropolymers. These includexylane, xyloglucan, arabinoxylan, arabinogalactan, glucuronoxylan,glucomannan and galactomannan. Monomeric components of hemicelluloseinclude, but are not limited to: D-galactose, L-galactose, D-mannose,L-rhamnose, L-fucose, D-xylose, L-arabinose, and D-glucuronic acid. Thisclass of polysaccharides is found in almost all cell walls along withcellulose. Hemicellulose is lower in weight than cellulose and cannot beextracted by hot water or chelating agents, but can be extracted byaqueous alkali. Polymeric chains of hemicellulose bind pectin andcellulose in a network of cross-linked fibers forming the cell walls ofmost plant cells.

The term “pectin” as used herein refers to a class of plant cell-wallheterogeneous polysaccharides that can be extracted by treatment withacids and chelating agents. Typically, 70-80% of pectin is found as alinear chain of α-(1-4) -linked D-galacturonic acid monomers. Thesmaller RG-I fraction of pectin is comprised of alternating (1-4)-linked galacturonic acid and (1-2)-linked L-rhamnose, with substantialarabinogalactan branching emanating from the rhamnose residue. Othermonosaccharides, such as D-fucose, D-xylose, apiose, aceric acid, Kdo,Dha, 2-O-methyl-D-fucose, and 2-O-methyl-D-xylose, are found either inthe RG-II pectin fraction (<2%), or as minor constituents in the RG-Ifraction. Proportions of each of the monosaccharides in relation toD-galacturonic acid vary depending on the individual plant and itsmicro-environment, the species, and time during the growth cycle. Forthe same reasons, the homogalacturonan and RG-I fractions can differwidely in their content of methyl esters on GalA residues, and thecontent of acetyl residue esters on the C-2 and C-3 positions of GalAand neutral sugars.

The term “inhibitor” refers to organic and inorganic compounds that whenpresent above a certain concentration, defined as the “inhibitoryconcentration,” impair a biocatalyst during a fermentation process. Theinhibitory concentration is dependent upon the inhibitor, thebiocatalyst, and the process conditions combined. Examples of inhibitorsinclude, but are not limited to, fermentation products, pretreatmentproducts, fermentation intermediates, carbon source, and feedstockcomponents.

The term “volumetric productivity” is defined as the amount of productper volume of media in a fermentor per unit of time. In someembodiments, the productivity may be expressed as the amount of productper unit of time, e.g., g/hr, when the volume of the fermentor is fixedat a specific volume.

The term “specific productivity” is defined as the rate of formation ofthe product. To describe productivity as an inherent parameter of themicroorganism or biocatalyst and not of the fermentation process,productivity is herein further defined as the specific productivity in gproduct per g of cell dry weight (CDW) per hour (g product g CDW⁻¹ h⁻¹).

The term “yield” is defined as the amount of product obtained per unitweight of raw material and may be expressed as g product /g substrate.Yield may be expressed as a percentage of the theoretical yield.“Theoretical yield” is defined as the maximum amount of product that canbe generated per a given amount of substrate as dictated by thestoichiometry of the metabolic pathway used to make the product. Forexample, if the theoretical yield for one typical conversion of glucoseto isobutanol is 0.41 g/g, the yield of butanol from glucose of 0.39 g/gwould be expressed as 95% of theoretical or 95% theoretical yield.

The term “tolerance” is defined as the ability of the biocatalyst tomaintain its specific productivity at a given concentration of aninhibitor. The term “tolerant” describes a biocatalyst that maintainsits specific productivity at a given concentration of an inhibitor. Forexample, if in the presence of 2% of an inhibitor a biocatalystmaintains the specific productivity that it had at 0 to 2% of aninhibitor, the biocatalyst is tolerant to 2% of the inhibitor, or has atolerance to 2% of the inhibitor.

The term “rate of inhibition” is defined as the rate of decrease of thespecific productivity of a biocatalyst relative to the increasedconcentration of an inhibitor, at inhibitor levels above the inhibitoryconcentration.

The term “resistance” is defined as a property of a biocatalyst thatleads to a low rate of inhibition in the presence of increasingconcentrations of an inhibitor in the fermentation broth. The term “moreresistant” describes a biocatalyst that has a lower rate of inhibitiontowards an inhibitor than another biocatalyst with a higher rate ofinhibition towards the same inhibitor. For example, suppose twobiocatalysts, A and B, are both tolerant to 2% (w/w) of an inhibitor andboth a specific productivity of 1 g product g CDW⁻¹ h⁻¹. If at 3% (w/w)inhibitor concentration biocatalyst A has a specific productivity of 0.5g product g CDW⁻¹ h⁻¹ and biocatalyst B has a productivity of 0.75 gproduct g CDW⁻¹ h⁻¹, then biocatalyst B is more resistant thanbiocatalyst A.

The term “titre” (or “titer”, which can be used interchangeably) isdefined as the strength of a solution or the concentration of asubstance in solution. For example, the titre of a biofuel precursor ina fermentation broth is described as g of biofuel precursor in solutionper liter of fermentation broth.

The term “primarily” in reference to a component of a composition of thepresent invention (e.g., a composition comprised “primarily of butenedimers”) refers to a composition which comprises at least 50% of thereferenced component.

The term “biofuel precursor” refers to an organic molecule in which allof the carbon contained within the molecule is derived from biomass, andis thermochemically or biochemically converted from a feedstock into theprecursor. A biofuel precursor may be a biofuel in its own right or maybe configured for conversion, either chemically or biochemically, into abiofuel with different properties. Biofuel precursors include, but arenot limited to, 1-propanol, 2-propanol, 1-butanol, 2-butanol,isobutanol, 1-pentanol, isopentanol (3-methyl-1-butanol), 3-pentanol,2-methyl-1-butanol, or neopentanol.

The term “byproduct” means an undesired product related to theproduction of biofuel or biofuel precursor. Byproducts are generallydisposed of as waste, thereby increasing the cost of the process.

The term “co-product” means a secondary or incidental product related tothe production of biofuel or biofuel precursor. Co-products havepotential commercial value that increases the overall value of biofuelprecursor production, and may be the deciding factor as to the viabilityof a particular biofuel or biofuel precursor production process.

The terms “alkene” and “olefin” are used interchangeably herein to referto non-aromatic hydrocarbons having at least one carbon-carbon doublebond.

The term “distillers dried grains”, abbreviated herein as DDG, refers tothe solids remaining after a fermentation, usually consisting ofunconsumed feedstock solids, remaining nutrients, protein, fiber, andoil, as well as biocatalyst cell debris. The term may also includesoluble residual material from the fermentation and is then referred toas “distillers dried grains and solubles” (DDGS).

The term “fusel alcohols” refers to alcohols such as propanols,butanols, and pentanols that are produced by microorganisms such asyeast during the fermentation process to make wine and beer.

“Carbon of atmospheric origin” as used herein refers to carbon atomsfrom carbon dioxide molecules that have recently (e.g., in the last fewdecades) been free in the earth's atmosphere. Such carbon atoms areidentifiable by the ratio of particular radioisotopes as describedherein. “Green carbon”, “atmospheric carbon”, “environmentally friendlycarbon”, “life-cycle carbon”, “non-fossil fuel based carbon”,“non-petroleum based carbon”, “carbon of atmospheric origin”, and“biobased carbon” are used synonymously herein.

“Carbon of fossil origin” as used herein refers to carbon ofpetrochemical origin. Carbon of fossil origin is identifiable by meansdescribed herein. “Fossil fuel carbon”, “fossil carbon”, “pollutingcarbon”, “petrochemical carbon”, “petrocarbon” and “carbon of fossilorigin” are used synonymously herein.

The term “isomerate” as used herein refers to the product of anisomerization reaction, for example a relatively high octane hydrocarbonmixture prepared by isomerizing simple alkanes.

“Renewably-based” or “renewable” denote that the carbon content of thebiofuel precursor and subsequent products is from a “new carbon” sourceas measured by ASTM test method D 6866-05, “Determining the BiobasedContent of Natural Range Materials Using Radiocarbon and Isotope RatioMass Spectrometry Analysis”, incorporated herein by reference in itsentirety. This test method measures the ¹⁴C/¹²C isotope ratio in asample and compares it to the ¹⁴C/¹²C isotope ratio in a standard 100%biobased material to give percent biobased content of the sample.“Biobased materials” are organic materials in which the carbon comesfrom recently (on a human time scale) fixated CO₂ present in theatmosphere using sunlight energy (photosynthesis). On land, this CO₂ iscaptured or fixated by plant life (e.g., agricultural crops or forestrymaterials). In the oceans, the CO₂ is captured or fixated byphotosynthesizing bacteria or phytoplankton. For example, a biobasedmaterial has a ¹⁴C/¹²C isotope ratio greater than 0. Contrarily, afossil-based material, has a ¹⁴C/¹²C isotope ratio of about 0. The term“renewable” with regard to compounds such as alcohols or hydrocarbons(linear or cyclic alkanes/alkenes/alkynes, aromatic, etc.) refers tocompounds prepared from biomass using thermochemical methods (e.g.,Fischer-Tropsch catalysts), biocatalysts (e.g., fermentation), or otherprocesses, for example as described herein.

A small amount of the carbon atoms of the carbon dioxide in theatmosphere is the radioactive isotope ¹⁴C. This ¹⁴C carbon dioxide iscreated when atmospheric nitrogen is struck by a cosmic ray generatedneutron, causing the nitrogen to lose a proton and form carbon of atomicmass 14 (¹⁴C), which is then immediately oxidized to carbon dioxide. Asmall but measurable fraction of atmospheric carbon is present in thefaun of ¹⁴CO₂. Atmospheric carbon dioxide is processed by green plantsto make organic molecules during the process known as photosynthesis.Virtually all forms of life on Earth depend on this green plantproduction of organic molecule to produce the chemical energy thatfacilitates growth and reproduction. Therefore, the ¹⁴C that forms inthe atmosphere eventually becomes part of all life forms and theirbiological products, enriching biomass and organisms which feed onbiomass with ¹⁴C. In contrast, carbon from fossil fuels does not havethe signature ¹⁴C:¹²C ratio of renewable organic molecules derived fromatmospheric carbon dioxide. Furthermore, renewable organic moleculesthat biodegrade to CO₂ do not contribute to global warming as there isno net increase of carbon emitted to the atmosphere.

Assessment of the renewably based carbon content of a material can beperformed through standard test methods, e.g. using radiocarbon andisotope ratio mass spectrometry analysis. ASTM International (formallyknown as the American Society for Testing and Materials) has establisheda standard method for assessing the biobased content of materials. TheASTM method is designated ASTM-D6866 .

The application of ASTM-D6866 to derive “biobased content” is built onthe same concepts as radiocarbon dating, but without use of the ageequations. The analysis is performed by deriving a ratio of the amountof radiocarbon (¹⁴C) in an unknown sample compared to that of a modernreference standard. This ratio is reported as a percentage with theunits “pMC” (percent modern carbon). If the material being analyzed is amixture of present day radiocarbon and fossil carbon (containing verylow levels of radiocarbon), then the pMC value obtained correlatesdirectly to the amount of biomass material present in the sample.

The transportation fuels of the present invention have pMC values of atleast about 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70,75, 80, 85, 90, 95, 100, inclusive of all values and subrangestherebetween.

The term “dehydration” refers to a chemical reaction that converts analcohol into its corresponding alkene. For example, the dehydration ofisobutanol produces isobutylene.

The term “aromatic compounds” or “aromatics” refers to hydrocarbons thatcontain at least one aromatic, six-membered ring. Examples of aromaticsrelative to this invention are benzene, toluene, ethyl benzene, propylbenzene, o-xylene, m-xylene, p-xylene, o-methyl ethyl xylene, and othermono- and di-alkylated benzenes.

The term “oligomerization” or “oligomerizing” refer to processes inwhich activated molecules such as alkenes are combined with theassistance of a catalyst to form larger molecules called oligomers.Oligomerization refers to the combination of identical alkenes (e.g.isobutylene) as well as the combination of different alkenes (e.g.isobutylene and propene), or the combination of an unsaturated oligomerwith an alkene. For example, isobutylene is oligomerized by an acidiccatalyst to form eight-carbon oligomers such as isooctene (e.g.,trimethylpent-1-enes and trimethylpent-2-enes) and twelve-carbonoligomers such as 2,2,4,6,6-pentamethylheptene,2,4,4,6,6-pentamethylhept-1-ene. In this example, isobutylene is amonomer, isooctene is a dimer of isobutylene, and2,2,4,6,6-pentamethylheptene is a trimer of isobutylene.

The term “rearrangement” refers to a chemical reaction in which alkylgroups on a hydrocarbon migrate to different positions on a carbonbackbone molecule during an oligomerization reaction. For example, theexpected product of the oligomerization of isobutylene withoutrearrangement is the trimer 2,4,4,6,6-pentamethylhept-1-ene. Withrearrangement, the methyl groups can migrate to other positions on theheptene backbone to produce hydrocarbons such as2,4,4,5,6-pentamethylheptene and 2,4,5,5,6-pentamethylheptene.

Typically, acidic catalysts catalyze both oligomerization andrearrangement, and thus both reactions typically occur nearlysimultaneously. Accordingly, as used herein the term “oligomerization”refers to the combination of alkenes in the presence of a catalyst toform larger molecules, as described herein, as well as the rearrangementof the resulting oligomers to form various isomers as described herein,unless otherwise indicated.

As described herein, olefins or mixtures of olefins can be reacted toform aromatic hydrocarbons (including alkylated aromatic hydrocarbons)in the presence of an aromatization catalyst. The resulting aromatichydrocarbons can be reacted in the presence of olefins and anoligomerization catalyst to form more highly alkylated aromatichydrocarbons. For example, benzene can be reacted with isobutylene inthe presence of an oligomerization catalyst as described herein to formt-butylbenzene or di-t-butylbenzenes. Similarly, toluene can be reactedin the presence of an oligomerization catalyst and isobutylene to formt-butylmethylbenzenes, etc. The term “oligomerization” thus can alsoinclude the “alkylation” of aromatic hydrocarbons in the presence of anoligomerization catalyst and olefins. Catalysts specifically intended oroptimized for the alkylation of aromatics are also termed alkylation oralkylating catalysts, and catalysts specifically intended or optimizedfor oligomerization are termed oligomerization catalysts.Oligomerization and alkylation can, in some embodiments be carried outsimultaneously in the presence of a single catalyst capable of carryingout both reactions, or in other embodiments can be carried out asseparate reactions using separate oligomerization and alkylationcatalysts.

The term “aromatization” refers to processes in which hydrocarbonstarting materials, typically alkenes or alkanes, are converted intoaromatic compounds (e.g., benzene, toluene, and/or xylenes) bydehydrocyclodimerization.

The term “reaction zone” refers to the part of a reactor or series ofreactors where the substrates and chemical intermediates contact acatalyst to ultimately form product. The reaction zone for a simplereaction may be a single vessel containing a single catalyst. For areaction requiring two different catalysts, the reaction zone can be asingle vessel containing a mixture of the two catalysts, a single vesselsuch as a tube reactor which contains the two catalysts in two separatelayers, or two vessels with a separate catalyst in each which may be thesame or different.

The term “conventional fuels” or “non-renewable” fuels refers to anyliquid fuel in which all of the carbon is originally derived from afossil sources, such as petroleum, natural gas, and coal.

The term “fuel additive” refers to any component of liquid fuel,representing less than 30% of the total fuel volume, which is added tothe fuel to impart specific performance properties to the fuel. Fueladditives include, but are not limited to octane enhancers for gasoline;cetane enhancers for diesel fuel; anti-static additives to enhancestatic charge dissipation; anti-icing additives to reduce the formationof ice crystals, and prevent the plugging of fuel filters at lowtemperatures; and anti-microbial additives to prevent fungal andbacterial growth at water/fuel interfaces. While all currently-used fueladditives are derived from non-renewable or fossil sources, such aspetroleum, natural gas, and coal, new fuel additive products may also bederived from renewable, biomass-derived sources.

The term “ASTM” refers to the American Society of Testing and Materials,which defines testing procedures and specifications for all petroleumproducts manufactured and sold commercially. For example, thespecification for gasoline is D4814; for aviation fuels, D1655; and fordiesel fuels, D975 .

The terms “Research Octane Number (RON)” and “Motor Octane Number (MON)”are measures of gasoline engine performance. RON is defined by ASTMmethods D2699 and D2885, and MON is defined by ASTM methods D2700 andD2885. Anti-knock index is defined by the arithmetic average of the twooctane numbers: (RON+MON)/2 .

The term “Cetane Number” is defined as measure of diesel engineperformance by ASTM method D613, and is roughly analogous in its usageto octane numbers used in gasoline engines. A close approximation to theCetane Number is the Cetane Index, which can be computed according toASTM D976 .

The term “Derived Cetane Number” or DCN is another measure of dieselfuel ignition performance as defined in ASTM methods D7170-08 orD6890-08.

The term “gasoline” refers to a mixture typically comprising primarilyhydrocarbon compounds that can be used to operate spark ignition engines(e.g., automotive engines), and is more volatile than jet fuel or dieselfuel. Gasoline can also include additives such as alcohols and otheroxygenated organic compounds. In practical terms, the mixture ofhydrocarbons and optional additives called gasoline must at least meetASTM D4814 specifications.

The term “diesel fuel” refers to a mixture typically comprisingprimarily hydrocarbon compounds that can be used to operate a dieselengine. In practical terms, the mixture of hydrocarbons called dieselfuel must meet key ASTM specifications for diesel fuel listed in ASTMspecification D975. Typical petroleum-based diesel fuels consist ofprimarily linear alkanes with C₁₄-C₁₅ alkanes as the major component,and lesser amounts of smaller and larger alkanes.

The term “jet fuel” refers to a mixture typically comprising primarilyhydrocarbon compounds that can be used to operate a jet engine. Jet fuelcan also include optional non- hydrocarbon additives. In practicalterms, the mixture of hydrocarbons and optional additives called jetfuel must at least meet key ASTM specifications for jet fuel listed inASTM specification D1655. Typical petroleum-based jet fuels consistprimarily of straight chain alkanes, with C₁₂ alkanes as the majorcomponent, and lesser amounts of aromatics and smaller and largeralkanes.

A “fuel precursor” refers to a mixture comprising hydrocarbons(aliphatic and/or aromatic hydrocarbons) that does not meet one or moreof the respective fuel specifications (e.g., the ASTM requirementsdescribed herein applicable to spark ignition fuels, diesel fuels, orjet fuels), but which can be adjusted to meet these specifications byblending an appropriate amount (e.g., typically up to about 10%, up toabout 20%, up to about 30%, up to about 40%, or up to about 50%) of theappropriate hydrocarbons.

The term “Weight Hourly Space Velocity” or “WHSV” refers to the weightof a reactant that is passed over a given weight of catalyst in a flowreactor configuration over an hour.

The term “saturated” refers to the oxidation state of a hydrocarbonmolecule in which all bonds are single bonds between carbon andhydrogen. Saturated acyclic hydrocarbons have a general molecularformula of C_(n)H_(2n+2).

The terms “terephthalates”, “isophthalates”, and “phthalates” refers toboth esters, free acids, and salts of terephthalic acid, isophthalicacid, and phthalic acid, unless expressly indicated otherwise.

As indicated above, the compositions of transportation fuels (e.g., jetand diesel fuels) are not defined at a molecular level. Instead,transportation fuels are defined as mixtures of typically aliphatic and(optionally) aromatic hydrocarbons that meet a collection of physicalproperties and specifications (e.g., as described in ASTM D1655, D 4817,D975, D910). All engines and turbines that use these fuels are designedto use mixtures (typically primarily hydrocarbons) with these specificproperties. If a biofuel is to be widely used as a transportation fuelreplacement, it must also meet this collection of physical propertiesand specifications.

For jet fuel or aviation turbine fuel, the key ASTM specificationsrelated to intrinsic fuel properties are measured by the followingtests: flash point, distillation temperature range, density, freezingpoint, viscosity, net heat of combustion, smoke point, naphthalenecontent, aromatic content, thermal oxidation stability, gum content, andacidity. Jet fuel volatility affects the performance of the fuel,especially its ability to be ignited in jet engine, and safety andhandling of the material both on and off the aircraft. Flash pointmeasures the minimum temperature a liquid must be at to form a flammablevapor mixture with air above its surface. It is measured by heating aquantity of the fuel until its surface can be ignited by a flame or anelectric ignition source. The specification for jet fuel flash point isa minimum 38° C. and is measured using ASTM method D56 or D3828. Thephysical distillation temperature range of a jet fuel is a measure ofthe type and behavior of the various hydrocarbon molecules in themixture. Jet fuel physical distillation temperature range is measured byASTM method D86. The specification for jet fuel is 10% of the mass ofthe fuel is recovered at maximum of 205° C. and the final boiling pointof the last bit of material is at a maximum of 300° C. The density of ajet fuel must be constant since transfer equipment and pumps functionvolumetrically and fuel tanks on aircrafts are designed to hold fixedvolumes of jet fuel. Jet fuel density or specific gravity is measured byASTM method D1298 or D 4052 and must be in the range of 775 to 840 kg/m³at 15° C. API gravity is another way of measuring jet fuel density andis measured by comparing the gravity of the jet fuel on an arbitraryscale from 0 to 100 with water having an API gravity of 10 on the scale.The API gravity range for jet fuel is between 37 and 51.

Low temperature operability of jet fuels is essential because jetaircraft operate at high altitudes where temperatures are typicallybetween −60° C. and −40° C. If the jet fuel freezes solid or even cloudsup during operation at these temperatures, the aircraft will cease tofly. Freezing point measures the lowest temperature at which thematerial remains a liquid. The specification for the freezing point ofjet fuel is a maximum of −40° C. for Jet A (jet fuel used within theUnited States) or a maximum of −47° C. for Jet A-1 (jet fuel used oninternational flights) measured by ASTM method D7154. Viscosity measuresthe ability of the fuel to flow. The jet fuel viscosity specification isa maximum of 8.0 mm²/s measured by ASTM method D445.

The combustion properties of jet fuel must be in specification to ensurethat the fuel functions properly. Net heat of combustion measures theenergy content of the fuel and is critical because it indirectlydetermines how far an aircraft can fly. The higher the energy density ofa fuel the better, but the specification for jet fuel net heat ofcombustion is a minimum of 42.8 MJ/kg measured by ASTM method D4809.Smoke point measures the combustion quality of the fuel and is inverselycorrelated with radiant heat transfer in jet engine combustors. Thesmoke point is also an indicator of soot forming potential of a fuel. Ingeneral, the higher the smoke point, measured by burning the fuel in awick-fed lamp and measuring the flame size at which smoking occurs, thehigher quality the fuel and the longer the jet engine combustor partlifetimes. The jet fuel smoke point specification is a minimum of 25 mmmeasured by ASTM method D1322. Combustion quality is also measured bythe amount of aromatic organic compounds in the jet fuel. In general,high amounts of naphthalenes burn hotter than other hydrocarbons,limiting the lifetime of jet engine parts. The specification fornaphthalene content in jet fuel is a maximum of 3% measured by ASTMmethod D1840. Similarly, high aromatics in jet fuel affect combustionquality, especially heat transfer and soot formation. The specificationfor aromatic content in jet fuel is a maximum of 25% measured by ASTMmethod D1319.

Jet fuel must be stable when stored and when exposed to the temperatureextremes during operation. In a jet engine, jet fuel is used as a heatsink and lubricant meaning that it is exposed to most of the movingparts of the engine at fairly high temperatures. Jet fuel hightemperature stability is measured by ASTM method D3241. In this method,jet fuel is heated and recirculated through a filter to captureparticles that form by the thermal oxidation of the fuel. Additionally,the recirculated fuel is passed over a polished aluminum surface toidentify oxidized material that may discolor it, causing the fuel tofail the test. The specifications for this test are after 2.5 hours ofrecirculation at a temperature of 260° C., the maximum pressure dropacross the in-line filter unit is 25 mm Hg and the tube is discoloredless than 3 units on the Jet Fuel Thermal Oxidation Test (JFTOT) scale.Jet fuel low temperature stability is determined by measuring the gumcontent of fuel using ASTM method D381. In this method, heated air orsteam is used to evaporate a portion of jet fuel to dryness and theresidue is weighed to measure the amount of non-volatile compounds inthe fuel. The specifications for gum content are a maximum of 7 mg/100mL of jet fuel, although typical values for jet fuels used in the fieldare ˜2 mg/100 mL of jet fuel. To prevent corrosion of engine componentsas the jet fuel lubricates and cools the engine, the acidity of the fuelmust be kept low. Acidity of jet fuel is measured by ASTM method D3242and has a specification of a maximum of 0.10 mg potassium hydroxide/g ofjet fuel to neutralize the acid in the fuel. Acidity is also measuredusing a copper corrosion test described in ASTM method D130. This testmeasures the potential of a given fuel to corrode a clean copper strip.The experiment is conducted at elevated temperatures, usually for 2hours, and corrosion is graded visually on a 1-5 scale, with 1 beingessentially no change in the appearance of the copper strip. The coppercorrosion specification for jet fuel is 1.

Conventional jet fuels are complex mixtures of aliphatic (80-90%) andaromatic (10-20%) hydrocarbons that are distilled from crude oil in arefinery. Crude oil is a heterogeneous mixture of thousands of differenthydrocarbons that widely varies depending upon the source of the crudeoil. Conventional jet fuel is produced by first distilling crude oil andtaking “cuts” from the distillation column that correspond to mixturesthat come close to meeting jet fuel specifications. The “cuts” are thenfinished off by blending in additional refined material such as othercrude oil distillates or chemically altered material to meetspecifications. Although the exact composition of a jet fuel can vary,in general, jet fuels are mixtures of linear and branched aliphatichydrocarbons with a molecular weight distribution centered around C₁₂hydrocarbons.

For diesel fuels the key ASTM specifications are measured by thefollowing tests: flash point, distillation temperature range, viscosity,cetane number, aromatic composition, and copper corrosion test. Thereare two major grades of diesel fuel, #1 and #2, with the latter beingthe most commonly used in general commerce, and in particular, thetrucking industry. For many of the key specifications, the requirementsfor #1 diesel fuels are similar to, or somewhat less demanding than, theanalogous ASTM specifications for jet fuels. The requirements for #2diesel fuels reflect the higher average molecular weights and boilingranges of these fuels. In cases where jet fuel fails certainspecifications (such as copper corrosion, smoke point, etc.), this fuelcan be downgraded and sold as #1 grade diesel fuel (provided it meetscetane number specifications). Red dyes are added to some diesel fuelsand can be used to distinguish them from jet and other grades of dieselfuel.

Diesel fuel is generally as or less volatile than other fuels such asgasoline and jet fuel. Like these fuels, the volatility of diesel fuelis measured by flash point and distillation range. Diesel fuel flashpoint is measured using ASTM method D93. #1 grade diesel fuel isrequired to have a minimum flash point of 38° C., whereas the flashpointfor #2 grade diesel fuel must be at least 52° C. Diesel fueldistillation range is measured using ASTM method D86. The distillationrange requirement for #2 grade diesel fuel is that 90% of the fuel berecovered in the distillation range 282-338° C. For #1 grade dieselfuel, the distillation range requirement is a maximum temperature of288° C. for this 90% fraction to be recovered.

The low temperature operability of diesel fuel depends upon where thefuel is used. Generally, in colder climates the fuel should beformulated to not freeze solid or even begin to “cloud” when stored.Because of the enormous diversity of geographies, environments, andweather conditions under which diesel engines must operate, there are nooverall, specific cold property specifications for diesel fuel. This isin distinct contrast to jet fuel, which is almost always used under thevery cold conditions of high altitudes. Rather than setting hundreds ofdiesel specifications for cold properties, sellers and distributorsnegotiate diesel compositions specific to their own geographic,environmental, and seasonal requirements. In virtually all cases,desired cold-flow properties can be obtained by mixing varyingproportions of #1 grade diesel fuel (better cold flow—close inproperties to jet fuel) and #2 grade diesel fuel (much heavier, thicker,and more viscous). Additionally, several ASTM cold flow specificationsare recommended to characterize these fuel blends, including: ASTMmethod D2500 for cloud point which indicates the beginning of fuelcrystallization, ASTM method D4539 for low temperature flow, and ASTMmethod D6371 for cold filter plug point which is predictive of when fuelfilters will fail under cold conditions. Under cold conditions where asignificant portion of #1 grade diesel fuel must be mixed with #2 gradediesel fuel to ensure engine operability, the higher distillationrequirements of #2 diesel fuel are waived. The viscosity of diesel fuelis determined using ASTM method D445. In the case of #2 grade dieselfuel, the required viscosity is 1.9-4.1 mm²/s at 40° C., and therequired viscosity of #1 grade diesel fuel is 1.3-2.4 mm²/s at 40° C.

The engine performance of diesel fuels is determined by an engineoperability test which measures the cetane number, and by the amount ofaromatic compounds found within the fuel. Cetane number is determinedusing ASTM method D613 (or alternatively, derived cetane number measuredby ASTM D1707-08 or D6890-08), and a minimum cetane number of 40 isrequired for both #1 and #2 grade diesel fuels. Aromatic compounds indiesel fuel must be limited because large amounts of them can increaseparticulate air emissions, soot and deposit formation in the engines,and incomplete fuel combustion. The maximum aromatic content of dieselfuels is measured using ASTM method D1319 and is specified to be 35%. Analternative to this test is the computed “cetane index”, which iscomputed by other distillation data according to ASTM method D976-80.

The stability of diesel fuel is partially determined by its reactionwith metals over a period of time using a copper corrosion testdescribed in ASTM method D130. This test measures the potential of agiven fuel to corrode a clean copper strip. The experiment is conductedat elevated temperatures, usually for 2 hours, and corrosion is gradedvisually on a 1-5 scale, with 1 being essentially no change in theappearance of the copper strip. The copper corrosion specification fordiesel fuel is 3.

Like diesel and jet fuels, gasoline is defined not by its composition,but by its ability to function in a spark ignition engine in veryspecific ways. For gasoline the ASTM key specification are defined byASTM D4814. Also included in this document are the specifications for aseries of ASTM methods used to determine whether or not gasoline and itsblends are suitable fuels. The specifications can be roughly dividedinto two categories. The first category describes properties that areinherent to composition of the gasoline, such as vapor pressure, energydensity, octane number, water solubility, thermal oxidation stability,gum content, and drivability. In general, these properties can only beadjusted by modifying the amounts and types of organic molecules thatmake up the gasoline. For example, if the octane number of a gasolinemixture is low, it can be raised by adding high octane components to themixture provided that the other important properties of the mixture donot fall out of specification. The key ASTM methods relevant to thegasoline compositions of the present invention fall within the firstcategory.

The second category of gasoline specifications describes properties thatare caused by contamination of the mixture either during or afterprocessing, especially during storage of the fuel under inadequateconditions. Properties in this second category include water content andacidity. Gasoline mixtures that measure out of specification for theseproperties can be treated to bring the mixture into specification. Forexample, excess water can be removed from gasoline by phase separationand acid can be neutralized.

The distillation range of gasoline is a property that captures manydifferent key aspects of how the gasoline composition behaves in acombustion engine to produce usable energy. For example, volatilecompounds are necessary for proper ignition of the fuel in thecombustion chamber of the engine. Additionally, less volatile but energydense compounds are required to increase overall fuel performance,especially mileage. The distillation curve of a gasoline mixture ismeasured using ASTM method D86, and the specification is calibrated byhow the typical hydrocarbon mixtures that comprise gasoline behave in anengine. When a substantial amount of the hydrocarbon component in agasoline mixture is replaced with a different type of organic compound,i.e. an alcohol such as n-butanol or isobutanol, the distillation curvewill differ from what is specified in ASTM D4814, even though the blendhas similar, if not identical, engine performance compared to unblendedgasoline. For this reason, the distillation curve specification is notused to describe the gasoline compositions of the present invention.

The vapor liquid ratio specification describes the amount of vapor thatforms above a given volume of liquid gasoline at atmospheric pressure,and is a measure of the volatility of the gasoline. The vapor liquidratio specification has both performance and environmental impactimplications. The performance aspect of the test measures the tendencyof the fuel to form combustible vapor mixtures inside the engine, andthe environmental impact aspect of measures the tendency of the fuel torelease volatile organic compounds into the environment. The optimumvapor liquid ratio of a gasoline mixtures is a balance between beingjust volatile enough to perform well in an engine, but not too volatileto leak from fuel tanks in volumes that are detrimental to air quality.The vapor liquid ratio is measured using ASTM method D2533. Thespecification for vapor liquid ratio is a maximum ratio of 20 at a giventemperature, depending upon the season that the gasoline is used. Ingeneral, higher ratio blends (ones containing increased amounts of morevolatile compounds) are used in the winter months. The temperature atwhich a vapor liquid ratio reaches 20 puts the mixture into a vapor lockclass which determines, in conjunction with other fuel properties, whichtime of year, and where in the country, the gasoline can be used. Thegasoline blends embodied herein meet the vapor liquid ratiospecifications appropriate for each season and in each state of theUnited States. Additionally, refinery products that fail to meet ASTMgasoline specifications and state and federal regulations for vaporpressure may be brought into specification by blending in compositionsof the present invention that lower the vapor pressure without alteringother fuel properties.

Vapor pressure measures the tendency of the mixture to vaporize from itsliquid surface and, as described above, affects both engine performanceand environmental impact of the gasoline. Vapor pressure can be measureda number of different ways using ASTM methods D4953, D5190, D5191, andD5482. The specification for vapor pressure is a maximum of 7.8 to 15psi at 100° F., depending upon what time of the year and where thegasoline is to be used. In some embodiments, blends of renewablehydrocarbons with gasoline have a vapor pressure that meets ASTMspecifications appropriate to the time and place of its use as gasoline.In yet another embodiment, a mixture of hydrocarbons with low octaneand/or high vapor pressure, e.g. raffinate from a refinery, which cannotnormally be blended with gasoline in high proportions is brought intoASTM specification by blending such hydrocarbon mixtures withcompositions of the present invention.

Aviation gasoline (Avgas) is used in aircraft with internal combustionreciprocating piston engines. The Wankel engine is another type ofinternal combustion engine, which uses a rotary design to convertpressure into a rotating motion, and can also use Avgas. There are manydifferent models of piston engine aircraft, such as Husky, Eagle, Pitts,Cessna, Piper, and Bellanca, which use different grades of Avgas.Aviation gasoline has a very high octane number which generally requiresthat it primarily be compromised of highly branched alkanes such asisooctane. Ideally, aviation gasoline is a mixture of C₅ to C₈hydrocarbons that as a mixture meet the key ASTM specifications foraviation gasoline in ASTM D910. Usually, because of inefficiencies inrefinery operations, the octane number of the branched hydrocarbons usedto make aviation gasoline is less than 100. To increase the octanenumber of this material, tetraethyl lead is added. The inventiondescribed herein, especially when the biofuel precursor used to makerenewable aviation gasoline is isobutanol, produced primarily C₈aliphatic hydrocarbons with octane numbers not higher than 100.

Tetraethyl lead (TEL) was used in automotive and aviation gasoline fuelsas octane enhancer for many decades. After passing the “Clean Air Act”in 1972, EPA launched an initiative to phase out TEL from automotivegasoline fuel. Although TEL has been banned in automotive gasoline fuel,it is still being used in aviation gasoline. TEL is a toxic material andEnvironmental Protection Agency has realized the implication of theairborne lead on health. In addition, aviation gasoline contains sulfurand high levels of aromatics. The impact of sulfur dioxide as an airpollutant is well researched and reported. At the present time, mostaviation gasoline, especially high octane aviation gasoline, containsTEL in part to satisfy the high octane requirement. For example,aviation gasoline 100 (Avgas 100) contains 0.77 g/L of TEL. Moreover,most aviation gasoline contains a high percentage of aromatics andsulfur as stated in ASTM D910. Renewable fuels with inherently highoctane number require less aromatics and TEL to meet aviation gasolinespecifications.

In contrast to fuels, fine chemicals are characterized by their chemicalcomposition rather than their physical and performance properties.However, when used as raw materials in manufacturing processes, finechemicals are generally required to have certain characteristics such asminimum purity levels. When fine chemicals are prepared frompetroleum-based feedstocks, such purity levels can be difficult and/orexpensive to achieve since petroleum-based feedstocks often comprisecomplex mixtures of hydrocarbons from which the desire starting materialmust be separated.

For example, xylenes are converted into either phthalic acid orphthalate esters by oxidation over a transition metal-containingcatalyst (see for example, Ind. Eng. Chem. Res. 2000, 39, p. 3958-3997for a review of the literature). Terephthalic acid (TPA) is thepreferred form for conversion into PET, but until recently it wasdifficult to produce TPA in a pure enough form for PET production.Dimethyl terephthalate (DMT) was traditionally produced in a purer formthan the TPA and can be used to manufacture PET as well. DMT is producedby esterification of the raw product of the TPA reactions describedabove with methanol and purification by distillation. A single stepprocess to produce DMT by oxidizing xylene in the presence of methanolwas developed by DuPont but is not often used due to low yields. All ofthese processes also produce monomethyl esters of the phthalates whichare hydrolyzed to faun the di-acids or further esterified to formdimethyl esters. Methods for producing TPA and DMT are taught in U.S.Pat. Nos. 2,813,119; 3,513,193; 3,887,612; 3,850,981; 4,096,340;4,241,220; 4,329,493; 4,342,876; 4,642,369; and 4,908,471).

TPA is produced by oxidizing p-xylene in air or oxygen over a catalystcontaining manganese and cobalt, although nickel catalysts have alsobeen used with some success. Acetic acid is used as a solvent for theseoxidation reactions and a bromide source such as hydrogen bromide,bromine, or tetrabromoethane is added to encourage oxidation of bothmethyl groups of the xylene molecule with a minimum of by-products. Thetemperatures of the reactions are generally kept between 80-270° C. withresidence times of a few hours. TPA is insoluble in acetic acid at lowertemperatures (i.e. below 100° C.), which allows separation andpurification of TPA by precipitation or crystallization. Similar methodsare also used to prepare isophthalic acid from m-xylene, or phthalicacid from o-xylene. However, xylenes are conventionally obtained bydistillation from petroleum, from which it is difficult to obtainsufficiently pure p-xylene free of m-xylene. Thus, contamination of adesired xylene isomer (e.g., p-xylene) with an unwanted xylene isomer(e.g., m-xylene) results in a mixture of e.g., isophthalic acid andterephthalic acid which can be difficult to separate. However, asdescribed herein, the processes of the present invention are capable ofproviding renewable fine chemicals having higher purity thanconventional petroleum-derived fine chemicals because the renewableprecursors for preparing renewable fine chemicals are generallyrelatively pure compounds or simple mixtures of compounds (e.g.alcohols) rather than complex mixtures of aliphatic, aromatic, andolefinic hydrocarbons. For example, the process of the present inventioncan be used to obtain terephthalic acid (or esters thereof) at higherlevels of purity compared to petroleum-derived terephthalic acid byproviding the starting p-xylene at higher levels of purity (as describedherein) compared top-xylene obtained by distillation from petroleum.Similarly, the process of the present invention can provide phthalicacid or isophthalic acid (or esters thereof) at relatively high puritycompared to conventional methods by providing the respective o-xylene orm-xylene starting materials at relatively high purity levels.

The compositions of the present invention are produced by reactingprecursors, e.g. isobutanol or isopentanol, produced by biocatalystsfrom biomass-derived feedstocks, in the presence of one or more chemicalcatalysts, typically a heterogeneous catalyst, to produce mixtures ofhydrocarbons that meet the fuel-defining ASTM specifications for therespective fuel (e.g., gasoline, diesel, or jet fuel). Renewable finechemicals can likewise be prepared by appropriate oxidation of one ormore hydrocarbons produced by the processes of the present inventiondescribed herein (e.g., an olefin or aromatic hydrocarbon). The catalystor catalysts can catalyze a single reaction (e.g., dehydration) or cancatalyze several reactions (e.g., dehydration, isomerization, andoligomerization).

Although the specific organic compounds of the biofuels and biofuelprecursors of the present invention can also be obtained from refineriesusing crude oil starting materials, biofuels and biofuel precursorsproduced via the fermentation of carbon sources such as carbohydratesand other biologically-derived materials, are qualitatively differentand have different fuel properties compared to compositions preparedfrom petroleum-derived sources. For example, as noted above,petroleum-derived fuels are distilled from a complex mixture ofhydrocarbons, whereas the biofuels of the present invention aretypically prepared by the dehydration, oligomerization, andhydrogenation of a single alcohol (e.g. isobutanol) or a mixture of afew different C₂-C₆ alcohols, and thus have quite different chemicalcompositions as the oligomers provided in a subsequent oligomerizationstep (as discussed herein) are formed from integral numbers of theintermediate olefins. For example, biofuels of the present inventionprepared from isobutanol would typically consist of a mixture ofbranched C₈, C₁₂, C₁₆ hydrocarbons; biofuels prepared frommethylbutanols (e.g. 2-methyl-1-butanol or 3-methyl-1-butanol) wouldtypically consist of branched C₁₀, C₁₅, C₂₀ hydrocarbons, etc., whereaspetroleum-based fuels would include both linear and branchedhydrocarbons, including C₉, C₁₀, C₁₁, C₁₃, C₁₄ hydrocarbons, etc. Thus,biofuels prepared by the claimed process are compositionally differentfrom conventional petroleum-based fuels.

In most embodiments of the present invention, the biofuel, biofuelprecursors, or fine chemical precursors are produced by biocatalyststhat convert carbon sources derived from biomass into the biofuels,biofuel precursors, or fine chemical precursors. Suitable carbon sourcesinclude any of those described herein such as starch, pre-treatedcellulose and hemicellulose, lignin, and pectin. The carbon source isconverted into a biofuel, biofuel precursor, or fine chemical precursorsuch as n-butanol or isobutanol by the metabolic action of thebiocatalyst (or by thermochemical methods, e.g. using Fischer-Tropschcatalysts). The carbon source is consumed by the biocatalyst andexcreted as a biofuel, biofuel precursor, or fine chemical precursor ina large fermentation vessel. The biofuel, biofuel precursor, or finechemical precursor is then separated from the fermentation broth,optionally purified, and in the case of biofuel or fine chemicalprecursors, subjected to further processes such as dehydration,oligomerization, hydrogenation, isomerization, aromatization,alkylation, blending, oxidation etc. to form a biofuel or renewable finechemical.

In most embodiments of the present invention, the biocatalyst produces aC₃-C₆ alcohol or mixture of alcohols. For example, the biocatalyst canbe a single microorganism capable of forming more than one type ofalcohol during fermentation (e.g. propanols and butanols). In mostembodiments however, a particular microorganism preferentially forms aparticular alcohol (e.g. isobutanol) during fermentation. In alternativeembodiments, the fermentation can be carried out with a mixture ofdifferent organisms, each producing a different alcohol duringfermentation, or different alcohols produced in different fermentationsusing different organisms can be combined, thereby providing a mixtureof two or more different alcohols.

Any suitable organism can be used in the fermentation step of theprocess of the present invention. For example, 2-propanol is produced byvarious Clostridia strains including Clostridium beijerinkii (Journal ofBacteriology, 1993, p. 5907-5915). Additionally, higher molecular weightalcohols such as isobutanol and various pentanols including isopentanolare produced by yeasts during the fermentation of sugars into ethanol.These fusel alcohols are known in the art of industrial fermentationsfor the production of beer and wine and have been studied extensivelyfor their effect on the taste and stability of these products. Recently,production of fusel alcohols using engineered microorganisms has beenreported (U.S. Patent Application No. 2007/0092957, and Nature, 2008,451, p. 86-89).

Alcohols prepared by fermentation in the process of the presentinvention include at least one of 1-propanol, 2-propanol. 1-butanol,2-butanol, isobutanol. 1-pentanol, 2-pentanol, 3-pentanol,2-methyl-1-butanol, 3-methyl-1-butanol, 1-hexanol, 2-hexanol, 3-hexanol,2-methyl-1-hexanol, 3-methyl-1-hexanol, or 4-methyl-1-hexanol.

Alternatively, the alcohols used to prepare the renewable compositionsof the present invention can be produced by converting biomass into amixture of alcohols at high heat over a catalyst containing copper,aluminum, chromium, manganese, iron, cobalt, or other metals and alkalimetals such as lithium, sodium, and/or potassium (Energy and Fuels,2008, 22, p. 814-839). The separate alcohols, including butanols andpentanols, optionally can be separated from the mixture by distillationand used to renewable compositions or compounds as described herein, orthe mixtures can be directly treated with appropriate catalyst(s) insubsequent processing steps, as described herein to make renewablecompounds, such as mixtures of aromatic compounds to blend with fuels.

The processes of the present invention for making renewablecompositions, as described herein, begin with the formation of alcoholsfrom biomass. In one embodiment, the alcohols are formed byfermentation, and the alcohol produced during fermentation is removedfrom the feedstock by various methods, for example fractionaldistillation, solvent extraction (e.g., with a renewable solvent such asrenewable oligomerized hydrocarbons, renewable hydrogenatedhydrocarbons, renewable aromatic hydrocarbons, etc. prepared asdescribed herein), adsorption, pervaporation, etc. or by combinations ofsuch methods, prior to dehydration. In other embodiments, the alcoholproduced during fermentation is not isolated from the feedstock prior todehydration, but is dehydrated directly as a dilute solution in thefeedstock.

In a particular embodiment, the alcohol produced during fermentation ofthe feedstock is isobutanol, which is removed from the feedstock in thevapor phase under reduced pressure (e.g. as a water/isobutanolazeotrope). In a very particular embodiment, the fermentor itself isoperated under reduced pressure without the application of additionalheat (other than that used to provide optimal fermentation conditionsfor the microorganism) or the use of distillation equipment, whereby thealcohol (e.g., isobutanol) is removed as an aqueous vapor (orazeotrope). This latter embodiment has the advantage of providing forseparation of the alcohol without the use of energy intensive orequipment intensive unit operations, as well as continuously removing ametabolic by-product of the fermentation and thereby improves theproductivity of the fermentation process. In other embodiments, theaqueous isobutanol removed from the fermentation is then furtherconcentrated from the water/isobutanol azeotrope by phase separation ofthe isobutanol phase. The resulting wet isobutanol can then be dried ordehydrated to isobutylene directly.

The post-fermentation processes for converting alcohols (e.g. C₃ to C₆alcohols) to renewable compositions (e.g., biofuels comprising C₆-C₂₄hydrocarbon mixtures) may be carried out separately, or may be combined.For example, when the biofuel precursor is isobutanol, the dehydrationstep (e.g., forming isobutene) and oligomerization step (e.g. formingdimers, trimers, etc.) can be carried out separately or combined into asingle process whereby isobutanol is contacted with a single catalystwhich catalyzes both dehydration and oligomerization. Similarly,hydrogenation of the unsaturated dimers, trimers, etc., formed duringoligomerization can be carried out as a separate step, or can beeffected during dehydration and/or oligomerization by the appropriateselection of catalyst and reaction conditions (e.g., temperature,hydrogen partial pressure, etc.).

As described herein, the various unit operations of the process of thepresent invention (e.g., dehydration, oligomerization, alkylation,hydrogenation, aromatization, oxidation, etc.) can be carried out indifferent reaction zones, or two or more chemically compatible unitoperations can be carried out in the same reaction zone, wherein thedifferent reaction zones can be in the same or different reactorvessels. When different unit operations are carried out in the samereaction zone, the appropriate catalysts can be physically mixed in thesame reaction zone, or in other embodiments the different catalysts canbe combined on a single support. The unit operations employed willdepend on the nature of the ultimate renewable product desired. Forexample, processes for preparing biofuels or biofuel precursors caninclude dehydration, oligomerization, and hydrogenation (and optionallyaromatization and alkylation), whereas processes for preparing renewableacrylates can include dehydration, optionally oligomerization,oxidation, and esterification, and processes for preparing renewablephthalates can include dehydration, optionally oligomerization,aromatization, oxidation, and esterification.

The first reaction catalyzed is the dehydration of the alcohol biofuelprecursor, e.g. isobutanol or isopentanol, into the correspondingalkene, e.g. isobutylene or isopentene. Depending upon the catalyst,dehydration of the alcohol can also be accompanied by rearrangement ofthe resulting alkene to form one or more isomeric alkenes. Ifisomerization occurs, the isomerization can occur concurrently with thedehydration, or subsequently to the dehydration.

The dehydration of alcohols to alkenes can be catalyzed by manydifferent catalysts. In general, acidic heterogeneous or homogeneouscatalysts are used in a reactor maintained under conditions suitable fordehydrating the alcohol. Typically, the alcohol is activated by anacidic catalyst to facilitate the loss of water. The water is usuallyremoved from the reaction zone with the product. The resulting alkeneeither exits the reactor in the gas or liquid phase (e.g., dependingupon the reactor conditions) and is captured by a downstreampurification process or is further converted in the reactor to othercompounds as described herein. For example, t-butyl alcohol isdehydrated to isobutylene by reacting it in the gas phase at 300-400° C.over an acid treated aluminum oxide catalyst (U.S. Pat. No. 5,625,109)or in the liquid phase at 120-200° C. over a sulfonic acid cationicexchange resin catalyst (U.S. Pat. No. 4,602,119). The water generatedby the dehydration reaction exits the reactor with unreacted alcohol andalkene product and is separated by distillation or phase separation.Because water is generated in large quantities in the dehydration step,the catalysts used are generally tolerant to water and a process forremoving the water from substrate and product may be part of any processthat contains a dehydration step. For this reason, it is possible to usewet (i.e., up to 95% water by weight) alcohol as a substrate for adehydration reaction and remove this water with the water generated bythe dehydration reaction. For example, dilute aqueous solutions ofethanol (up to 98% water by weight) can be dehydrated over a zeolitecatalyst with all water removed from the ethylene product stream afterthe dehydration step occurs (U.S. Pat. Nos. 4,698,452 and 4,873,392).Additionally, neutral alumina and zeolites will dehydrate alcohols toalkenes but generally at higher heats and pressures than the acidicversions of these catalysts. For example, neutral chromium treatedalumina will dehydrate isobutanol to isobutylene above 250° C. (U.S.Pat. No. 3,836,603).

In one embodiment of the invention described herein, the first step in aprocess to form a fuel is a dehydration step where aqueous mixtures ofbiofuel precursors that are alcohols, e.g. isobutanol, are fed into areactor containing an acidic solid phase catalyst and heated such thatthe alcohol is converted into an alkene, e.g. isobutylene.

In other embodiments, the aqueous alcohol mixtures comprise about 1%,about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%,about 70%, about 75%, about 80%, about 85%, about 90%, or about 95%water, inclusive of all values, ranges, and subranges therebetween.

The alkene foamed in the dehydration step can be transferred directly tothe oligomerization catalyst (e.g., in another reaction zone or anotherreactor), or can be isolated prior to oligomerization. In oneembodiment, the alkene is isolated as a liquid and optionally purified(e.g., by distillation) prior to oligomerization. Isolation of thealkene (or olefin) is advantageous in that the dehydration process isoptimally carried out under gas-phase conditions to remove water vapor,whereas the oligomerization is optimally carried out under liquid-phaseconditions, and thus isolation of the alkene allows the dehydration andoligomerization reactions to both be carried out under optimalconditions. Isolation of the alkene can refer to a process in which thealcohol produced by the biocatalyst (or thermochemical process) iscontinuously removed from the fermentor and dehydrated continuously toprovide alkene. The alkene can then be stored and later reacted further(e.g., oligomerization and/or aromatization and/or hydrogenation and/oroxidation), or the isolated alkene can be temporarily stored in aholding tank prior to e.g. oligomerization providing an integrated,continuous process in which each of the unit operations (e.g.,fermentation, dehydration, oligomerization, optional aromatization,optional alkylation, optional dehydration, optional oxidation, optionaldistillation into various fuel fractions, etc) run simultaneously andmore or less continuously, and the isolation of the alkene provides a“buffer” to processes upsets.

The second reaction catalyzed is the oligomerization of the alkeneproduced by dehydration of the alcohol as described above, intounsaturated aliphatic compounds, primarily dimers, trimers, tetramers,or pentamers, etc. of the corresponding alkene (depending upon thecatalyst and reaction conditions).

The renewable unsaturated aliphatic compounds prepared byoligomerization in the process of the present invention have three, twoor at least one double bond. On average, the product of theoligomerizing step of the process of the present invention has less thanabout two double bonds per molecule, in particular embodiments, lessthan about 1.5 double bonds per molecule. In most embodiments, theunsaturated aliphatic compounds (alkenes) have on average one doublebond.

Alkenes are reactive molecules that condense into oligomeric compounds(oligomerize) under a variety of conditions and with the assistance ofseveral different types of both heterogeneous and homogenous catalysts(G. Busca, “Acid Catalysts in Industrial Hydrocarbon Chemistry” ChemicalReviews, 2007, 107, 5366-5410). Of the many ways of oligomerizingalkenes, the most relevant processes for the production of fuels andfine chemicals depend upon acidic solid phase catalysts such as aluminaand zeolites (e.g. U.S. Pat. No. 3,997,621; U.S. Pat. No. 4,663,406;U.S. Pat. No. 4,612,406; U.S. Pat. No. 4,864,068; U.S. Pat. No.5,962,604). Methods for controlling the molecular weight distribution ofthe resulting oligomers has been reported including methods which formprimarily dimers including isooctane (U.S. Pat. No. 6,689,927), trimers(WO 2007/091862 A1), and tetramers and pentamers (U.S. Pat. No.6,239,321 B1). Typical methods for controlling oligomer size include theaddition of alcohols such as t-butanol and diluents such as paraffins.Additionally, higher molecular weight oligomers and polymers can beformed using similar catalysts reacting under different conditions. Forexample, low molecular weight polyisobutylene (up to 20,000 Daltons) canbe produced using a boron trifluoride complex catalyst (U.S. Pat. No.5,962,604).

If a mixture of different alkenes (e.g., derived from a mixture ofdifferent alcohols) is oligomerized, the resulting oligomer mixturecomprises the corresponding addition products formed by the addition oftwo or more alkenes which can be the same or different. For example if amixture of propenes and butenes is oligomerized, the product cancomprise “binary” or “dimer” addition products such as hexenes,heptenes, octenes; “ternary” or “trimer” addition products such asnonenes, decenes, undecenes, dodecenes, etc. Isobutylene is especiallyuseful as a key intermediate in the oligomerization reaction because itforms primarily branched hydrocarbons that are essential to meetinggasoline and jet fuel ASTM specifications. In some embodiments, theoligomerization reaction may be omitted, for example if the desiredproduct is a renewable fine chemical which can be prepared directly fromthe alkene produced in the dehydration reaction (e.g., acrylates can heproduced by oxidation of propene followed by esterification).Alternatively, in other embodiments fine chemicals may be prepared by aprocess incorporating oligomerization, e.g. if the ultimate finechemical has a higher carbon number than the carbon number of thealcohol produced in the fermentation step. For example, if the desiredfine chemical is a methacrylate (i.e., four carbon atoms), and thealcohol produced in the fermentation is ethanol (i.e., two carbonatoms), dimerization of the ethylene produced in the dehydration stepwould provide butenes which can be oxidized to methacrylate.

The third reaction catalyzed is the rearrangement of the alkene monomerduring oligomerization to introduce new branching patterns into thehydrocarbon products. Rearrangement can be important in achieving amixture of branched hydrocarbons that best meets gasoline and jet fuelspecifications without the need for oligomerizing a mixture of alkenes,derived from the corresponding mixture of alcohols. In some embodiments,rearrangement of the alkene may not be desired if the intended productis a fine chemical, or if a particular alkene isomer is the desiredproduct.

During the oligomerization reaction described above, alkyl and hydridegroup shifts occur that result in a mixture of isomers ofoligomerization products (U.S. Pat. No. 5,962,604). In some cases,isomerization of the oligomers is not desired because it can affect theoverall physical properties of the material that is being produced inunpredictable ways. In other cases, isomerization is preferred,especially if the starting alkene is deficient in certain keyproperties. For example, melting points of polymers made from n-butylenecan be decreased by isomerizing the n-butylene to isobutylene before orduring the polymerization (U.S. Pat. No. 6,323,384; U.S. Pat. No.5,107,050: U.S. Pat. No. 6,111,160) using catalysts and processesspecifically designed to isomerizes these compounds. Degree of branchingis a key parameter that affects many of the physical properties relatedto the performance of jet and diesel fuel. For example, the morebranched an alkane, the lower the melting point. For a mixture ofalkanes with a given molecular weight distribution, the mixturecontaining more branched alkanes will have a lower freezing point.Additionally, the acyclic alkanes in petroleum-based jet and dieselfuels are present in most of their possible isomers, giving these fuelstheir signature ranges of cold flow properties, ignitability, and energydensity. Biofuels that are jet or diesel fuels will generally be moresuccessful replacements if they, too, contain mixtures of isomers.

In some embodiments the dehydration and oligomerization/rearrangementsteps can be carried out separately. In other embodiments, thedehydration and oligomerization/rearrangement are carried out in asingle reaction zone using a catalyst which catalyzes both reactions.

The fourth reaction catalyzed (particularly for the production ofbiofuels) is the conversion of the alkene bonds in these hydrocarbonproducts into heat-stable saturated hydrocarbons (e.g., byhydrogenation). As indicated above, this reaction may be omitted invarious embodiments of the processes of the present invention, when thedesired product is not an alkane.

In most embodiments, the renewable saturated aliphatic compound formedafter hydrogenation in the process of the present invention is fullysaturated or partially saturated. On average, the product of saidhydrogenating step has less than about 0.5 double bonds per molecule, inparticular embodiments less than about 0.2 double bonds per molecule.

As described herein, some renewable compositions such as biofuels orrenewable fine chemicals comprise aromatic compounds, in which case theprocess of the present invention can include an aromatization step,either as a separate process or as a unit operation integrated into theprocess. In some embodiments, alkenes prepared by dehydration of arenewable alcohol (e.g. obtained by fermentation) are contacted with theappropriate aromatization catalyst to provide renewable aromaticcompounds. In other embodiments, unsaturated oligomers obtained from theoligomerization of alkenes are aromatized to provide higher molecularweight aromatics (e.g. typically more highly alkylated aromatics).

In some embodiments, each of the above unit operations can be carriedout in separate reaction zones. Alternatively, in other embodimentsvarious unit operations can be combined in a single reaction zone,whereby intermediates are immediately converted into the desiredproduct. For example, a single reaction zone can contain the appropriatecatalyst or mixture of catalysts whereby a renewable alcohol can bedehydrated and immediately oligomerized, or can be dehydrated,oligomerized, and aromatized, or can be dehydrated, oligomerized, andhydrogenated etc.

For the production of biofuels, once the starting material, e.g.isobutanol or isopentanol, is loaded into the reactor with thecatalyst(s), the reaction is maintained at a temperature and pressure(and if needed, under a reducing atmosphere such as H₂) that produces amixture of hydrocarbons that meets the appropriate biofuelspecifications. The resulting products are then separated (or removed)from the reactor, optionally purified, and optionally blended witharomatics produced from the starting material in a separate reaction tomeet the appropriate biofuel specifications. In processes of the presentinvention incorporating aromatization as a unit operation, the hydrogenproduced as a byproduct can be used to reduce alkenes (e.g. alkenesproduced by dehydration of alcohols and/or oligomeric alkenes producedin the oligomerization step) to saturated hydrocarbons. Thus in someembodiments of the process of the present invention, virtually allcarbon and hydrogen in the biofuel is renewable. Alternatively, thehydrogen or other reducing agent can be supplied from other sources.

In some embodiments of the process of the present invention, the processis carried out in an apparatus having a single reactor with one or morereaction zones in which various unit operations are carried out (e.g.dehydration, polymerization, hydrogenation, etc.). In other embodiments,the process of the present invention may require two or more reactors,each with one or more reaction zones, in which the two or more reactorsare appropriately interconnected to provide an integrated process. Forexample, renewable jet fuels which comprise a mixture of hydrocarbonsand aromatics can be prepared in an apparatus in which one or more ofdehydration, oligomerization, alkylation, and hydrogenation are carriedout in one or more reactors containing one or more reaction zones, andaromatization is carried out in a separate reactor, such that a portionof the alkenes and/or alkene oligomers formed in the dehydration and/oroligomerization reaction zones are fed to the aromatization reactor. Thearomatic compounds formed in the aromatization reactor can then becollected and/or mixed with the alkanes formed after hydrogenation, orfurther alkylated (e.g., in a separate alkylation reaction zone or inthe oligomerization reactions) before being collected and/or mixed withthe alkanes formed after hydrogenation. In addition, the hydrogenproduced during aromatization can be used in the hydrogenation reactionzone.

The process of the present invention can be optimized to provide aspecific biofuel or a specific biofuel precursor, or can be optimized toproduce a mixture of renewable hydrocarbons which can be separated intotwo or more different product streams, each of which is a differentbiofuel (e.g. renewable diesel or renewable jet fuel) or a differentbiofuel precursor (e.g. octane isomers or dodecane isomers), or one ofthe different product streams can be a particular biofuel, and anotherdifferent product streams can be a particular biofuel precursor.

Alternatively, the process of the present invention can be designed suchthat by modification of process conditions (e.g., temperature, pressure,or selection of catalyst, etc) a particular feedstock can be convertedto any particular desired biofuel or biofuel precursor. For example, theprocess can be designed such that by changing process conditions onecould obtain either renewable diesel fuel or renewable jet fuel.

The biofuel precursors can include a pure alcohol (e.g., isobutanol) orcan be a mixture of different C₂-C₆ alcohols, produced either byconversion of a feedstock with a mixture of different microorganisms, orby the combination of different C₂-C₆ alcohols produced by separatelyfermenting feedstocks in the presence of different microorganisms whichpreferentially produced different alcohols. For example, ethanol andisobutanol, separately produced by different fermentation processes canbe combined and subjected to dehydration, oligomerization,hydrogenation, and optionally aromatization processes. Alternatively,biofuel precursors can include alkenes or oligomers (e.g., alkenedimers, trimers, etc.) which when added to hydrocarbon mixtures canimprove the properties of the resulting composition to comply with theappropriate ASTM fuel specifications. For example, addition of biofuelprecursors to hydrocarbon mixture can improve the octane (e.g. MON andRON values) or cetane values, or improve low temperature performance ofthe fuel, etc.

The biofuels described in this invention can comprise mixtures ofhydrocarbons with molecular weight distributions similar to those ofpetroleum-derived fuels, i.e. the biofuel that replaces jet fuel is amixture of linear and branched hydrocarbons with a molecular weightdistribution centered around hydrocarbons containing 12 carbon atoms.These biofuels are produced from biofuel precursors such as isobutanoland isopentanol by reacting the precursors in chemical reactorscontaining catalysts that convert the precursors into mixtures ofhydrocarbons that fit the typical profile of jet fuel. However, biofuelsproduced by the processes of the present invention from a relativelypure precursor such as isobutanol or 2-methyl-1-butanol would producemixtures of hydrocarbons which are (or are derived from) dimers, trimer,tetramers, etc. of the alkene produced by dehydration of thecorresponding alcohol.

In one embodiment, a relatively pure biofuel precursor, e.g. isobutanol,formed by the fermentation of a biomass-derived feedstock is dehydratedin a chemical reactor that contains a solid phase catalyst thatcatalyzes both the dehydration and oligomerization of the alcohol toform precursors to, or forms gasoline, jet or diesel fuels. In anotherembodiment, an aqueous solution of biofuel precursor is fed to achemical reactor that contains a solid phase catalyst that catalyzesboth the dehydration and oligomerization of the alcohol to formprecursors to, or forms gasoline, jet or diesel fuels. In anotherembodiment, an alkene, e.g. isobutylene, formed by the dehydration of abiofuel precursor, e.g. isobutanol, is fed into a chemical reactorcontaining a catalyst that catalyzes the oligomerization of the alkeneto form precursors to, or forms gasoline, jet or diesel fuels. In yetanother embodiment, water and alkene, e.g. isobutylene, formed by thedehydration of a biofuel precursor, e.g. isobutanol, is fed into achemical reactor containing a catalyst that catalyzes theoligomerization of the alkene to form precursors to, or forms gasoline,jet or diesel fuels. In a particular embodiment, the jet fuel producedby the dehydration and oligomerization of isobutanol produced byfermentation is comprised of a distribution of oligomers of isobutylenein which a majority of the isomers are trimers of isobutylene containing12 carbon atoms. In another particular embodiment, the diesel fuelproduced by the dehydration and oligomerization of isobutanol reviews byfermentation is comprised of a distribution of oligomers of isobutylenein which a majority of the isomers are tetramers of isobutylenecontaining 16 carbon atoms. In still another particular embodiment, thegasoline produced by the dehydration and oligomerization of isobutanolproduced by fermentation is comprised of a distribution of oligomers ofisobutylene in which a majority of the isomers are dimers of isobutylenecontaining 8 carbon atoms. The oligomerization products are furtherreduced to saturated hydrocarbons by hydrogen, in some embodimentsderived from the aromatization of a second stream of alcohol or alkene,as described herein. In a particular embodiment, these aromatics areblended with the saturated hydrocarbons (e.g. trimers of isobutylene) toproduce jet fuel that meets ASTM specifications.

In one embodiment of the invention described herein, a biofuelprecursor, e.g. isobutanol, formed by the fermentation of abiomass-derived feedstock is dehydrated in a chemical reactor thatcontains a solid phase catalyst that catalyzes both the dehydration,oligomerization, and partial rearrangement of the alcohol to formprecursors to or to form jet fuels with increased isomer diversity,relative to a product formed by oligomerization without rearrangement,in the final product. In another embodiment, a linear biofuel precursor,e.g. n-butanol, formed by the fermentation of a biomass-derivedfeedstock is dehydrated in a chemical reactor that contains a solidphase catalyst that catalyzes both the dehydration, oligomerization, andrearrangement of the alcohol to form precursors to, or which formsgasoline, jet or diesel fuel with increased branching and isomerdiversity, relative to a product formed by oligomerization withoutrearrangement, in the final product. In another embodiment, the biofuelprecursor undergoing dehydration, oligomerization, and rearrangement isfed to the reactor as an aqueous solution. In yet another embodiment,the biofuel precursor is converted into an alkene in a separate reactor,and the alkene is fed into a reactor where it is oligomerized andrearranged to form precursors to, or which forms gasoline, jet or dieselfuels with increased branching and isomer diversity, relative to aproduct formed by oligomerization without rearrangement, in the finalproduct. In a particular embodiment, the jet fuel produced by thedehydration, oligomerization, and rearrangement of isobutanol producedby fermentation is comprised of a distribution of oligomers of butylenesin which a majority of the isomers are trimers of butylenes containing12 carbon atoms. In another embodiment, the diesel fuel produced by thedehydration, oligomerization, and rearrangement of isobutanol producedby fermentation is comprised of a distribution of oligomers of butylenesin which a majority of the isomers are tetramers of butylenes containing16 carbon atoms. In still another embodiment, the gasoline produced bythe dehydration, oligomerization, and rearrangement of isobutanolproduced by fermentation is comprised of a distribution of oligomers ofbutylenes in which a majority of the isomers are dimers of butylenescontaining 8 carbon atoms. The oligomerization products are subsequentlyreduced to saturated hydrocarbons by hydrogen derived from thearomatization of a second stream of alcohol or alkene, as describedherein. These aromatics are blended with the saturated hydrocarbons toproduce gasoline, jet or diesel fuel that meets ASTM specifications.

Suitable acid catalysts are selected from the group consisting ofinorganic acids, organic sulfonic acids, heteropolyacids, perfluoroalkylsulfonic acids, metal salts thereof, mixtures of metal salts, andcombinations thereof. The acid catalyst may also be selected from thegroup consisting of zeolites such as CBV-3020, ZSM-5, β Zeolite CP 814C,ZSM-5 CBV 8014, ZSM-5 CBV 5524 G, and YCBV 870; fluorinated alumina;acid-treated silica; acid-treated silica-alumina; acid-treated titania;acid-treated zirconia; heteropolyacids supported on zirconia, titania,alumina, silica; and combinations thereof. The acid catalyst may also beselected from the group consisting of metal sulfonates, metal sulfates,metal trifluoroacetates, metal triflates, and mixtures thereof; mixturesof salts with their conjugate acids, zinc tetrafluoroborate, andcombinations thereof.

Other acid catalysts that may be employed in this process of theinvention include inorganic acids such as sulfuric acid, phosphoricacid, hydrochloric acid, and nitric acid, as well as mixtures thereof.Organic acids such as p-toluene sulfonic acid, triflic acid,trifluoroacetic acid and methanesulfonic acid may also be used.Moreover, ion exchange resins in the acid form may also be employed.Hence, any type of acid catalyst known in the art may be employed.

Fluorinated sulfonic acid polymers can also be used as acid catalystsfor the process of the present invention. These acids are partially ortotally fluorinated hydrocarbon polymers containing pendant sulfonicacid groups, which may be partially or totally converted to the saltform. One particularly suitable fluorinated sulfonic acid polymer isNafion® perfluorinated sulfonic acid polymer, (E.I. du Pont de Nemoursand Company, Wilmington, Del.). One preferred form is Nafion® Super AcidCatalyst, a bead-form strongly acidic resin which is a copolymer oftetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octene sulfonylfluoride, converted to either the proton (H+), or the metal salt form.

A soluble acid catalyst may also be used during the method of theinvention. Suitable soluble acids include, those acid catalysts with apKa less than about 4, preferably with a pKa less than about 2,including inorganic acids, organic sulfonic acids, heteropolyacids,perfluoroalkylsulfonic acids, and combinations thereof. Also suitableare metal salts of acids with pKa less than about 4, including metalsulfonates, metal sulfates, metal trifluoroacetates, metal triflates,and mixtures thereof, including mixtures of salts with their conjugateacids. Specific examples of suitable acids include sulfuric acid,fluorosulfonic acid, phosphoric acid, p-toluenesulfonic acid,benzenesulfonic acid, phosphotungstic acid, phosphomolybdic acid,trifluoromethanesulfonic acid, 1,1,2,2-tetrafluoroethanesulfonic acid,1,2,3,2,3,3-hexapropanesulfonic acid, bismuth triflate, yttriumtriflate, ytterbium triflate, neodymium triflate, lanthanum triflate,scandium triflate, zirconium triflate, and zinc tetrafluoroborate.

For batch reactions, the acid catalyst is preferably used in an amountof from about 0.01% to about 50% by weight of the reactants, althoughthe concentration of acid catalyst may exceed 50% if the reaction is runin continuous mode using a packed bed reactor. A preferred range is0.25% to 5% by weight of the reactants unless the reaction is run incontinuous mode using a packed bed reactor. For flow reactors, the acidcatalyst will have WHSV values ranging from 0.1 to 20.

Other suitable heterogeneous acid catalysts include, for example, acidtreated clays, heterogeneous heteropolyacids and sulfated zirconia. Theacid catalyst can also be selected from the group consisting of sulfuricacid-treated silica, sulfuric acid-treated silica-alumina, acid-treatedtitania, acid-treated zirconia, heteropolyacids supported on zirconia,heteropolyacids supported on titania, heteropolyacids supported onalumina, heteropolyacids supported on silica, and combinations thereof.Suitable heterogeneous acid catalysts include those having an H₀ of lessthan or equal to 2.

The oligomerization process described above produces hydrocarbons thatmay contain at least one double bond. In general, double bonds are veryreactive and their presence in, for example jet fuel, is not desirablebecause they will spontaneously polymerize in an engine, which may causedamage. Accordingly, in most embodiments of processes for preparing jetfuel according to the present invention, such double bonds are removedby hydrogenation, for example using hydrogen gas derived from thearomatization of isobutanol or hydrocarbon derivatives of isobutanol(e.g., isobutylene). Alternatively, non-renewable hydrogen or otherhydrogen containing compounds such as borane may be used. The reductionof the double bond is catalyzed by Group VIII metals such as palladium,nickel, cobalt, rhodium or platinum dispersed in a heterogenous catalystmaterial (Advanced Organic Chemistry, 4^(th) edition, J. March, 1992).In particular embodiments, the dehydration, oligomerization,rearrangement, and reduction (hydrogenation) steps are carried out in asingle reactor containing a heterogenous catalyst complex capable ofcatalyzing all of these reactions. Alternatively, in other embodimentsthe oligomerized and rearranged product may be transferred into anadditional reactor for reduction over a different catalyst.

In other embodiments, hydrogenation is carried out in the presence of asuitable active metal hydrogenation catalyst. Acceptable solvents,catalysts, apparatus, and procedures for hydrogenation in general can befound in Augustine, Heterogeneous Catalysis for the Synthetic Chemist,Marcel Decker, New York, N.Y. (1996).

Many hydrogenation catalysts are effective, including (withoutlimitation) those containing as the principal component iridium,palladium, rhodium, nickel, ruthenium, platinum, rhenium, compoundsthereof, combinations thereof, and the supported versions thereof.

When the hydrogenation catalyst is a metal, the metal catalyst may be asupported or an unsupported catalyst. A supported catalyst is one inwhich the active catalyst agent is deposited on a support material e.g.by spraying, soaking or physical mixing, followed by drying,calcination, and if necessary, activation through methods such asreduction or oxidation. Materials frequently used as supports are poroussolids with high total surface areas (external and internal) which canprovide high concentrations of active sites per unit weight of catalyst.The catalyst support may enhance the function of the catalyst agent; andsupported catalysts are generally preferred because the active metalcatalyst is used more efficiently. A catalyst which is not supported ona catalyst support material is an unsupported catalyst.

The catalyst support can be any solid, inert substance including, butnot limited to, oxides such as silica, alumina, titania, calciumcarbonate, barium sulfate, and carbons. The catalyst support can be inthe form of powder, granules, pellets, or the like. A preferred supportmaterial of the present invention is selected from the group consistingof carbon, alumina, silica, silica-alumina, titania, titania-alumina,titania-silica, barium, calcium, compounds thereof and combinationsthereof. Suitable supports include carbon, SiO₂, CaCO₃, BaSO₄ TiO₂, andAl₂O₃. Moreover, supported catalytic metals may have the same supportingmaterial or different supporting materials.

In one embodiment of the instant invention, a more preferred support iscarbon. Further preferred supports are those, particularly carbon, thathave a surface area greater than 100-200 m²/g. Further preferredsupports are those, particularly carbon, that have a surface area of atleast 300 m²/g. Commercially available carbons which may be used in thisinvention include those sold under the following trademarks: Bameby &Sutcliffe™, Darco™, Nuchar™, Columbia JXN™, Columbia LCK™, Calgon PCB™,Calgon BPL™, Westvaco™, Norit™ and Barnaby Cheny NB™. The carbon canalso be commercially available carbon such as Calsicat C, Sibunit C, orCalgon C (commercially available under the registered trademarkCentaur®).

Preferred combinations of catalytic metal and support system includenickel on carbon, nickel on Al₂O₃, nickel on CaCO₃, nickel on TiO₂,nickel on BaSO₄, nickel on SiO₂, platinum on carbon, platinum on Al₂O₃,platinum on CaCO₃, platinum on TiO₂, platinum on BaSO₄, platinum onSiO₂, palladium on carbon, palladium on Al₂O₃, palladium on CaCO₃,palladium on TiO₂, palladium on BaSO₄, palladium on SiO₂, iridium oncarbon, iridium on Al₂O₃, iridium on SiO₂, iridium on CaCO₃, iridium onTiO₂, iridium on BaSO₄, rhenium on carbon, rhenium on Al₂O₃, rhenium onSiO₂, rhenium on CaCO₃, rhenium on TiO₂, rhenium on BaSO₄, rhodium oncarbon, rhodium on Al₂O₃, rhodium on SiO₂, rhodium on CaCO₃, rhodium onTiO₂, rhodium on BaSO₄, ruthenium on carbon, ruthenium on Al₂O₃,ruthenium on CaCO₃, ruthenium on TiO₂, ruthenium on BaSO₄, and rutheniumon SiO₂.

Raney metals or sponge metals are one class of catalysts useful for thepresent invention. A sponge metal has an extended “skeleton” or“sponge-like” structure of metal, with dissolved aluminum, andoptionally contains promoters. The sponge metals may also containsurface hydrous oxides, absorbed hydrous radicals, and hydrogen bubblesin pores. Sponge metal catalysts can be made by the process described inU.S. Pat. No. 1,628,190, the disclosure of which is incorporated hereinby reference.

Preferred sponge metals include nickel, cobalt, iron, ruthenium,rhodium, iridium, palladium, and platinum. Sponge nickel or spongecobalt are particularly suitable as catalysts. The sponge metal may bepromoted by one or more promoters selected from the group consisting ofGroup IA (lithium, sodium, and potassium), IB (copper, silver, andgold), IVB (titanium and zirconium), VB (vanadium), VIB (chromium,molybdenum, and tungsten), VIIB (manganese, rhenium), and VIII (iron,cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, andplatinum) metals. The promoter can be used in an amount useful to givedesired results. For example, the amount of promoter may be any amountless than 50% by weight of the sponge metal, preferably 0 to 10% byweight, more preferably 1 to 5% by weight.

Sponge nickel catalysts contain mainly nickel and aluminum. The aluminumis typically in the form of metallic aluminum, aluminum oxides, and/oraluminum hydroxides. Small amounts of other metals may also be presenteither in their elemental or chemically bonded form, such as iron and/orchromium, and may be added to the sponge nickel to increase activity andselectivity for the hydrogenation of certain groups of compounds. It isparticularly preferred to use chromium and/or iron promoted spongenickel as a catalyst.

Sponge cobalt catalysts also contain aluminum and may contain promoters.Preferred promoters are nickel and chromium, for example in amounts ofabout 2% by weight based on the weight of the catalyst. Examples ofsuitable sponge metal catalysts include Degussa BLM 112W, W. R. GraceRaney® 2400, Activated Metals A-4000™, and W. R. Grace Raney® 2724.

As stated above, useful catalytic metals include component iridium,palladium, rhodium, nickel, ruthenium, platinum, rhenium; and usefulsupport materials include carbon, alumina, silica, silica-alumina,titania, titania-alumina, titania-silica, barium, calcium, particularlycarbon, SiO₂, CaCO₃, BaSO₄ and Al₂O₃. A supported catalyst may be madefrom any combination of the above named metals and support materials. Asupported catalyst may also, however, be made from combinations ofvarious metals and/or various support materials selected fromsubgroup(s) of the foregoing formed by omitting any one or more membersfrom the whole groups as set forth in the lists above. As a result, thesupported catalyst may in such instance not only be made from one ormore metals and/or support materials selected from subgroup(s) of anysize that may be formed from the whole groups as set forth in the listsabove, but may also be made in the absence of the members that have beenomitted from the whole groups to form the subgroup(s). The subgroup(s)formed by omitting various members from the whole groups in the listsabove may, moreover, contain any number of the members of the wholegroups such that those members of the whole groups that are excluded toform the subgroup(s) are absent from the subgroup(s). For example, itmay be desired in certain instances to run the process in the absence ofa catalyst formed from palladium on carbon.

The optimal amount of the metal in a supported catalyst depends on manyfactors such as method of deposition, metal surface area, and intendedreaction conditions, but in many embodiments can vary from about 0.1 wt% to about 20 wt % of the whole of the supported catalyst (catalystweight plus the support weight). A more preferred catalytic metalcontent range is from about 0.1 wt % to about 10 wt % by weight of thewhole of the supported catalyst. A further preferred catalytic metalcontent range is from about 1 wt % to about 7 wt % by weight of thewhole of the supported catalyst. Optionally, a metal promoter may beused with the catalytic metal in the method of the present invention.Suitable metal promoters include: 1) those elements from groups 1 and 2of the periodic table; 2) tin, copper, gold, silver, and combinationsthereof; and 3) combinations of group 8 metals of the periodic table inlesser amounts.

Temperature, solvent, catalyst, pressure and mixing rate are allparameters that affect the hydrogenation. The relationships among theseparameters may be adjusted to effect the desired conversion, reactionrate, and selectivity in the reaction of the process.

In one embodiment, the hydrogenation temperature is from about 25° C. to350° C., more preferably from about 50° C. to about 250° C., and mostpreferred from about 50° C. to 200° C. The hydrogen pressure ispreferably about 0.1 to about 20 MPa, more preferably about 0.3 to 10MPa, and most preferably about 0.3 to 4 MPa. The reaction may beperformed neat or in the presence of a solvent. Useful solvents includethose known in the art of hydrogenation such as hydrocarbons, ethers,and alcohols (where the alcohols and ethers, or hydrocarbon solvents canbe renewable). Alcohols are most preferred, particularly lower alkanolssuch as methanol, ethanol, propanol, butanol, and pentanol. Where thereaction is carried out according to the preferred embodiments,selectivities in the range of at least 70% are attainable whereselectivities of at least 85% are typical. Selectivity is the weightpercent of the converted material that is a saturated hydrocarbon wherethe converted material is the portion of the starting material thatparticipates in the hydrogenation reaction.

Upon completion of the hydrogenation reaction, the resulting mixture ofproducts may be separated by a conventional method, such as for example,by distillation, by crystallization, or by preparative liquidchromatography.

For jet fuels which must pass the very restrictive JFTOT test describedabove, oxygen-containing compounds are also not desired. Jet fuelscontaining oxygen-containing compounds which fail the JFTOT test areusually used as diesel fuels or diesel fuel precursors

Petroleum-derived jet fuels are mixtures of hydrocarbons having carbonnumbers distributed around C₈ to C₁₆, most of which are normal paraffins(i.e. straight chain alkanes) and isoparaffins (i.e., branched alkanes),naphthenes (i.e. cycloalkanes) and aromatics. As discussed herein,renewable jet fuels are produced by dehydration of a renewable alcohol,e.g. propanol or isobutanol, to produce alkenes, e.g. propylene orisobutylene, which undergo oligomerization in the presence of an acidcatalyst. Under these conditions, the precursors are converted intomixtures of hydrocarbons, which are subsequently hydrogenated, resultingin a mixture that meets the typical specifications of jet fuel. Becausethe starting materials for the renewable jet fuels of the presentinvention are e.g., C₃ and i-C₄ alcohols, renewable jet fuelcompositions will be mainly branched aliphatic hydrocarbons. However,Fisher Tropsch synthetic jet fuels have shown that the complete lack ofaromatic hydrocarbons is associated with a lower density fuel and aninability to swell nitrile elastomer o-rings needed to provide adequateperformance for aircraft fuel system seals. The United State Departmentof Defense has indicated that the minimum density requirement is ofsecondary importance, but it was realized that at least some aromaticsare needed to provide elastomer compatibility (Energy & Fuels 2007, 21,1448).

There is presently no commercial process to produce C₆-C₈ aromatics fromrenewable sources. Instead, C₆-C₈ aromatics are currently produced bycatalytic cracking and catalytic reforming of petroleum-derivedfeedstocks. In particular, the catalytic reforming process uses lighthydrocarbon “cuts” like liquefied petroleum gas (C₃ and C₄) or lightnaphtha (especially C₅ and C₆). There are three main processes forconversion of these petroleum-derived feedstocks to C₆-C₈ aromatics: M-2Forming (Mobil), Cyclar (UOP) and Aroforming (IFP-Salutec).

In the past three decades, new catalysts have been developed to producepetrochemical grade benzene, toluene, and xylene (BTX) from lowmolecular weight alkanes in a single step. The process can be describedas “dehydrocyclodimerization and dehydrogenation” over one catalyst andin single reaction zone. In refineries liquefied petroleum gas streamscontaining a mixture of C₃ and C₄ alkanes are aromatized to produce amixture of benzene, toluene, and all three isomers of xylene. Ethylbenzene may also be produced in these reactions.

The conversion of small alkanes and alkenes into aromatic compounds,such as xylene, has been reported many times over the years using avariety of alumina and silica based catalysts and reactorconfigurations. For example, the Cyclar process developed by UOP and BPfor converting liquefied petroleum gas into aromatic compounds uses agallium-doped zeolite (Appl. Catal. A, 1992, 89, p. 1-30). Othercatalysts reported in the patent literature include bismuth, lead, orantimony oxides (U.S. Pat. Nos. 3,644,550 and 3,830,866), chromiumtreated alumina (U.S. Pat. Nos. 3,836,603 and 6,600,081B2), rheniumtreated alumina (U.S. Pat. No. 4,229,320) and platinum treated zeolites(WO 2005/065393 A2). The conversion of alkenes and alkanes into aromaticcompounds is a net oxidation reaction that releases hydrogen from thealiphatic hydrocarbons. If no oxygen is present, hydrogen gas and lightalkanes such as methane and ethane are by-products. If oxygen ispresent, the hydrogen is converted into water. In an embodiment of thepresent invention, the hydrogen and light alkanes by-products arerenewable sources of these compounds. In another embodiment, therenewable hydrogen and light alkanes are used in a biorefinery toproduce additional renewable compounds. In a traditional refinery thatproduces aromatics, these light compounds are collected and usedthroughout the refinery. These and other light hydrocarbons (C₁-C₆) arealso produced by direct cracking of the hydrocarbon feedstocks at thehigh heats and pressures needed to generate the aromatics. In anotherembodiment, these cracking products are renewable and used in abiorefinery to produce additional renewable compounds.

The hydrocarbon feedstocks used to form aromatic compounds in aconventional petroleum refinery are primarily mixtures of hydrocarbons.As a result, the aromatics produced by petroleum refineries are mixturesof aromatics, which are typically used directly in fuel blends. Forchemical applications, the pure aromatic compounds must be separated andpurified from these mixtures. However, in a large-scale refinery,producing pure streams of specific aromatics can be expensive anddifficult.

In contrast, the process of the present invention can readily providerelatively pure aromatic compounds at a cost which is competitive withthat of conventional refineries. For example, biomass derived isobutanol(e.g. from fermentation) can be dehydrated and oligomerized todiisobutylene in a reactor containing a metal-doped zeolite catalyst.The diisobutylene is then selectively converted to aromatics in highyield. Of the xylenes produced, the selectivity to p-xylene is greaterthan 90%. Such selectivity has been demonstrated on laboratory scaleusing pure t-butanol (U.S. Pat. No. 3,830,866), isobutylene (U.S. Pat.No. 3,830,866), and diisobutylene (U.S. Pat. No. 6,600,081 B2). Thus,the process of the present invention provides pure alcohol startingmaterials such as butanols and pentanols, as described herein, at costcompetitive or lower than conventional refineries. In addition, thealkenes produced by dehydration of these alcohols in the process of thepresent invention are more reactive than the primarily saturated alkanestraditionally used in a refinery to produce aromatics, which allow theuse of milder reaction conditions resulting in improved selectivity forthe desired single product (e.g., p-xylene).

For example, renewable xylene can be prepared by the process of thepresent invention by aromatizing renewable isooctene. The resultingproduct contains only negligible amounts of renewable benzene andtoluene, and predominately comprises xylene(s), from which renewablep-xylene can be recovered at very high purity.

Thus, in some embodiments of the process of the present invention,renewable aromatics—benzene, toluene, and xylene (BTX)—are produced bythe dehydrocyclodimerization and dehydration of alkanes, e.g. isobutane,prepared from renewable alcohols, e.g. isobutanol, reacted with ahydrotreating catalyst. The hydrodeoxygenation process can be carriedout over Co/Mo, Ni/Mo or both catalysts and in the presence of hydrogenat reasonable temperatures (e.g., ˜150° C.). When isobutanol is used asa starting material in this reaction, the product is highly selective(˜90%) isobutane with more than 95% conversion.

The renewable alkenes, e.g. propylene or isobutylene, formed by theprocess of the present invention can be aromatized using variouscatalysts, for example zeolite catalyst, e.g. H-ZSM-5 (Ind. Eng. Chem.Process Des. Dev. 1986, 25, 151) or GaH-ZSM-5 (Applied Catalysis 1988,43, 155), which sequentially oligomerizes the olefin, cyclizes theoligomerized olefins to naphthenes, and dehydrates the naphthene to thecorresponding aromatic compound. Alternatively, a metal oxide catalystcan be used in presence of molecular oxygen. This latter type ofcatalyst dimerizes the olefin to the corresponding diene, which isfurther cyclized to the corresponding aromatic compound. Because sucharomatization conditions are more severe than oligomerizationconditions, these two processes are generally carried out as separateprocess steps.

The first step of the process to produce renewable aromatics fromrenewable alcohol precursors, e.g., propanol, isobutanol, orisopentanol, is the dehydration of the alcohol. For example, a renewablealcohol is fed into a reactor containing an acidic solid phase catalystand heated to dehydrate the alcohol to an alkene, e.g. propene,isobutene, or isopentene. In the production of renewable aromatics, thedehydration step of the renewable alcohol produces almost exclusivelyalkenes, with are more reactive to the aromatization process than thealkanes used in conventional aromatization processes.

Alcohol dehydration:

-   -   C₃H₈O→C₃H₆+H₂O    -   C₄H₁₀O→C₄H₈+H₂O

The second step is the conversion of alkenes to C₆-C₈ aromatics. In someembodiments, the production of renewable aromatics from renewablepropylene or isobutylene is achieved according to one of the followingprocesses:

Aromatization of light olefins using zeolites, i.e. H-ZSM-5 orGaH-ZSM-5:

-   -   C₃→C₆-C₈ Aromatics    -   C₄→C₆-C₈ Aromatics

Oxidative dehydrodimerization of light olefins using metal oxide/O₂:

-   -   2 C₃H₆→C₆H₁₀→benzene+H₂O    -   2 C₄H₈→C₈H₁₄→p-xylene+H₂O

Dimerization of isobutylene to isooctene followed by its aromatizationusing eta-alumina doped with Cr, Zr, and other elements:

-   -   2 i-C₄H₈→i-C₈H₁₆→p-xylene+3 H₂

In one embodiment, the invention described herein comprises anintegrated process for producing jet fuel from a fermentation productsuch as isopropanol, n-butanol, isobutanol, isopentanol, and2-methyl-1-butanol. The renewable jet fuel of the present inventioncomprises a mixture of aliphatic and aromatic hydrocarbons that meetsall ASTM specifications for jet fuel. The renewable jet fuel producedfrom this process can be used in place of jet fuel produced by apetroleum refinery without modification of transportation, storage, andfueling equipment. The renewable jet fuel from this process can be usedin existing jet turbine engines without modifying the engines.Substantially all of the carbon in the renewable jet fuel produced withthis process is derived from renewable sources (e.g., at least about 90%of the carbon is derived from renewable sources). The aliphatichydrocarbon component is produced from alcohols by a combination ofdehydration, oligomerization, and reduction to saturated hydrocarbons.The aromatic component is produced by directly reacting the alcohols ortheir oligomers over an aromatization catalyst in an oxygen-freeenvironment. The aromatization process produces aromatic compounds suchas xylenes and other alkyl benzenes that are blended with the saturatedhydrocarbons to meet ASTM specifications for jet fuel. The aromatizationprocess also produces enough hydrogen gas to stoichiometrically reducethe oligomers to saturated hydrocarbons. Because the hydrogen is derivedfrom the fermentation product, no additional carbon sources such asbiomass or natural gas are required to produce the hydrogen needed toremove olefins from the jet fuel mixture. The carbon and hydrogen in therenewable jet fuel is completely derived from renewable sources.

For example, isobutanol can be converted into primarily p-xylene,generating 3 chemical equivalents of hydrogen gas. Isobutanol is alsoconverted into C₁₋₂-branched oligomers. Each molecule of oligomers thatis generated by the oligomerization process contains a single olefinicbond which must be converted into a saturated hydrocarbon before it isacceptable for use in a jet fuel. An ideal jet fuel which meets all keyASTM standards contains about 25 mole percent of p-xylene (or otherrenewable aromatics) and 75 mole percent of aliphatic hydrocarbons. Togenerate the 75 mole percent of saturated hydrocarbons from the olefinicoligomers, 75 mole percent of hydrogen is required. For moston-specification combinations of aromatic and aliphatic hydrocarbons,the conversion of the starting alcohol into the aromatic portion of thefuel will produce approximately as much hydrogen gas as will be neededto convert the aliphatic portion of the fuel into saturated hydrocarbon.An integrated process which starts with a single alcohol such asisobutanol will be able to produce a jet fuel that meets all ASTMspecifications without the need for additional carbon or hydrogen.Alternatively, a biorefinery that produces aromatic compounds for jetfuel will produce additional aromatic compounds for use with other fuelsand chemical processes, generating additional hydrogen that can be usedas needed to remove olefinic compounds from the jet fuel.

Other renewable alcohols, including ethanol, 1- and 2-propanol, 1- and2-butanol, and pentanols such as 1-, 2-, 3-pentanol, 2-methyl-1-butanol,and isopentanol, are converted to aromatic compounds using similar setsof reactions and catalysts and producing 3 equivalents of hydrogen peraromatic ring produced. These alcohols are also oligomerized toaliphatic hydrocarbons that are reduced with the hydrogen by-product tosaturated compounds and blended with the aromatics to generate renewablejet fuel that meets ASTM specifications. These alcohols can be usedalone or in combination with each other and/or isobutanol to producemixtures of aromatic and aliphatic hydrocarbons that meet ASTMspecifications for jet fuel. These mixtures are produced in anintegrated process that does not require additional carbon and hydrogeninputs to create jet fuel from the starting alcohols.

The aromatization of propylene or isobutylene will mainly produce a BTXmixture (C₆-C₈ aromatics), which are too light for renewable jet fuel.Aromatics more suitable for use in jet fuel can be obtained byalkylation of BTX. The alkylation of aromatics is carried outindustrially using mineral acids (e.g. solid phosphoric acid) andFriedel-Crafts catalysts (e.g. AlCl₃-HCl). One of the most commerciallyimportant examples of aromatic alkylation is the alkylation of benzenewith ethylene or propylene to produce ethyl benzene and cumene,respectively. Ethyl benzene and cumene are starting materials for theproduction of phenol and styrene (Catalysis Review 2002, 44(3), 375).However, economic, engineering and environmental factors have driven thedevelopment of new technologies in which solid acids, such aszeolite-based catalysts, are used to catalyze the direct alkylation ofbenzene with propylene or ethylene. Several commercial processes havebeen developed in the past few years for the alkylation of aromaticswith light alkenes based on zeolite catalysts. A common concern in theseprocesses is that for more highly reactive olefins (reactivity increaseswith increasing length of the olefin chain) oligomerization of theolefin will compete with alkylation of the aromatic, and thus higharomatic to olefin ratios are needed. Furthermore, becausemonoalkyl-aromatics are more reactive that non-alkylated aromatics (dueto the electron donating effects of the alkyl substituent), mono-alkylaromatics are more readily alkylated to dialkyl or trialkyl-aromatics.However, such concerns are not relevant for the production of fuels,because the oligomerization and alkylation of aromatics can be done inone step, thereby saving capital costs.

Renewable benzene, toluene and xylene can be alkylated with renewablepropylene or isobutylene to produce heavier aromatics compounds that aremore suitable for renewable jet fuel (Ind. Eng. Chem. Res. 2008, 47,1828). Furthermore, aromatic alkylation conditions are similar tooligomerization conditions and both steps can be performed in onereactor or one reaction zone by reacting a stream of C₆-C₈ aromaticswith alkenes in the presence of a suitable catalyst, as shown in FIG. 1.Under excess olefin conditions, both aromatic alkylation andoligomerization will take place. Alternatively, it is well known thatalcohols can also act as alkylating agents under acid catalyticconditions. Accordingly, in other embodiments, aromatics can bealkylated with alcohols under excess alcohol conditions (i.e.dehydration of the alcohol and subsequent oligomerization occur in thepresence of aromatics, resulting in alkylation of aromatics). In stillother embodiments, oligomerization/aromatic alkylation using C₃-C₄olefins can be carried in the presence of an acid catalyst in onereaction zone or in one reactor having two or more reaction zones. Inparticular embodiments, C₃-C₄ alcohols can be used as alkylating agentsfor aromatics, in the presence of an acid catalyst, in one reactionzone.

The renewable jet fuel produced by the process of the present inventioncan be used directly as a jet fuel or blended with jet fuel derived frompetroleum for use in jet engines. Renewable jet fuels include jet fuelscomprising from about 0.01% to about 100% of hydrocarbons (aliphatic andaromatic) prepared from renewable feedstocks as described herein. Inother embodiments, the jet fuels of the present invention comprise anamount of renewable hydrocarbons (aromatic and aliphatic of at leastabout 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%,65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% inclusive of all values andsubranges therebetween. Because the jet fuel described herein isrenewable, it has a distinct carbon isotopic signature which can be usedto identify its presence in blends. The renewable jet fuel derived fromthis process will contain measurable amounts of ¹⁴C due to its originfrom plant material whereas petroleum-based jet fuel containsessentially none. The increase in ¹⁴C will be measurable in blends ofany concentration of renewable jet fuel with petroleum-based jet fuel.Additionally, the biological pathways used to produce the C₃-C₅ alcoholstarting materials react at different rates with molecules containingdifferent carbon isotopes. The accumulation of these different reactionrates results in a difference in ¹³C in the renewable product relativeto an internationally recognized standard. The renewable jet fueldescribed herein will have a distinctive isotopic signature dependentupon which alcohols are used to produce it. Traces of the isotopicsignature will be apparent in blends of renewable jet fuel withpetroleum-based jet fuel. A discussion of how isotope effects accumulatein renewable materials and examples of composition of matter patentsthat use these effects are J. Agric. Food Chem. 1997, 45, p. 2042-2046;J. Agric. Food Chem. 2005, 53, p. 197-201; New Phytologist, 2004, 161,p. 371-385; Naturwissenschaften 2003, 90, p. 537-552; U.S. Pat. No.7,169,588 B2; and U.S. Patent Application No. US 2007/0202062 A1.

In addition, the biofuel compositions of the present invention (e.g.,gasoline, jet or diesel) are also quite different from petroleum-derivedfuel compositions. The chemical conversion of a relatively purerenewable alcohol (e.g., isobutanol produced by fermentation) or asimple mixture of two or more renewable alcohols by dehydration,oligomerization, isomerization, hydrogenation, and optionallyaromatization typically provides a characteristic mixture of brancheddimers, trimers, tetramers, etc., whereas petroleum-derived fuels aredistillates and/or blends of complex hydrocarbon mixtures. For example,as shown in FIGS. 3-7, conventional petroleum-based fuel compositionscomprise a complex mixture of hydrocarbons produced by combining variousdistillation “cuts”, whereas the biofuel compositions of the presentinvention comprise a much simpler mixture of hydrocarbons. An additionaladvantage to using renewable fuels of this invention is the ability totune the final fuel properties by controlling the amount and types ofoligomers that are produced. In traditional petroleum-based fuelrefining such tuning is impractical because all carbon from crude oilmust be utilized, limiting flexibility. For example, the cold flowproperties of a renewable diesel fuel of this invention can be increasedby changing the catalyst in the oligomerization step to one that favorsslightly more branched products.

The process of the present invention may be carried out in batch,sequential batch (i.e. a series of batch reactors) or in continuous modein any of the equipment customarily employed for continuous processes(see, for example, H. S. Fogler, Elementary Chemical ReactionEngineering, Prentice-Hall, Inc., NJ, USA). Byproducts such as thecondensate water formed as the product of the dehydration reaction,hydrogen produced by an aromatization reaction, etc. can be removed byseparation methods customarily employed for such separations.

In some embodiments, the alcohol produced by fermentation of anappropriate renewable feedstock is renewable isobutanol, which isdehydrated over an acid catalyst in a first reaction zone to formisobutylene. The isobutylene is oligomerized in a second reaction zoneunder suitable conditions (high heat) to provide primarily dimers,trimers, or tetramers (e.g. depending upon whether the desire product isgasoline, jet fuel, or diesel, or additives for any of these fuels). Theoligomerized diisobutylene is then hydrogenated in a third reaction zoneto provide the corresponding branched, saturated hydrocarbons (e.g.,2,2,4-trimethylpentane, 2,2,4,4,6-pentamethylheptane, and2,2,4,4,6,6,8-heptamethylnonane, and isomers thereof). The “crude”product of the process comprises a mixture of C₈, C₁₂, and C₁₆hydrocarbons, in which the predominant component is either one or moreC₈ isomers, one or more C₁₂ isomers, or one or more C₁₆ isomers,depending upon the reaction conditions employed. In other embodiments,the dehydration and oligomerization steps can be carried out in a singlereaction zone to form unsaturated oligomers (e.g., dimers, trimers, andtetramers) directly from isobutanol. In still other embodiments, thedehydration, oligomerization, and hydrogenation steps can be carried outin a single reaction zone to form branch, saturated hydrocarbons asdescribed above directly from isobutanol.

In alternative embodiments, the alcohol produced by fermentation of anappropriate renewable feedstock is renewable isobutanol, which isdehydrated over an acid catalyst in a 1st reaction zone to formisobutylene. The isobutylene is recovered and reacted under high heatand pressure conditions in a second reaction zone containing one or morecatalysts known to aromatize aliphatic hydrocarbons. The resultingaromatic product, comprising p-xylene, is recovered and optionally shownby known methods to be renewable. In another embodiment, the isobutanolis dehydrated and dimerized over an acid catalyst, and the diisobutyleneis recovered and reacted in a second reactor to form renewable p-xylene.In yet another embodiment, isobutanol containing up to 15% water isdehydrated, or alternatively dehydrated and oligomerized, and thenfurther reacted as described herein to form a renewable aromatic productcomprising p-xylene. In another embodiment, hydrogen and the C₁-C₃hydrocarbon byproducts of an aromatization reaction as described hereinare recovered for later use in other reactions. In still otherembodiments, the dehydration and aromatization step occurs in a singlereaction zone using a single catalyst. The aromatic compounds are eitherpurified to obtain pure streams of individual aromatic products or themixture of aromatics is partially purified or used directly as anaromatic blendstock for gasoline or jet fuel.

In other embodiments, the alcohol produced by fermentation of anappropriate renewable feedstock is renewable 1-propanol or 2-propanol,which is dehydrated or dehydrated and oligomerized over an acid catalystand then reacted over a second catalyst to produce benzene, toluene, andxylenes in addition to hydrogen and C₁-C₂ hydrocarbons. In yet otherembodiments, the renewable alcohols are C₄ alcohols such as 1-butanoland 2-butanol, C₅ alcohols such as 2-methyl-1-butanol, isopentanol and2-pentanol, or C₆ alcohols such as 2-methyl-1-pentanol, isohexanol and2-hexanol that are dehydrated or dehydrated and oligomerized and thenreacted over a second catalyst to produce xylenes and other alkyl- anddialkyl-benzenes in addition to hydrogen and C₁-C₃ hydrocarbons. In anembodiment, aromatization of these alcohols is performed in a singlereaction zone. In yet another embodiment, the alcohols contain up tosaturating levels of water. The aromatic compounds are either purifiedto obtain pure streams of individual aromatic products, or the mixtureof aromatics is partially purified or used directly as a aromaticblendstock for jet fuel.

In other embodiments, mixtures of C₂-C₁₀ alcohols and/or C₂-C₂₀hydrocarbons produced by the thermochemical processing of biomass aretreated over appropriate catalysts to form renewable aromatic compoundsand hydrogen and C₁-C₃ hydrocarbons. The aromatic compounds are eitherpurified to obtain pure streams of individual aromatic products or themixture of aromatics is partially purified or used directly as aaromatic blendstock for gasoline or jet fuel.

The materials produced by the processes described above are tested fortheir renewable carbon content using the test method described in ASTMD6866. The alcohols are primarily produced by the fermentation ofrecently harvested biomass (within the last 2 years). Therefore, theratio of carbon isotopes of the recently produced product isapproximately equal to the ratio of carbon isotopes of the currentbiomass. Older biomass is also used to produce these materials and willhave carbon isotope ratios greater than zero which demonstrate that theyare also renewable.

The methods of the present invention also provide compositions ofaromatic compounds, especially benzene, toluene, alkylbenzenes, xylenes,and dialkylbenzenes. Using ASTM method D6866, the carbon content ofthese materials is shown to be renewable. It is the intent of thisdisclosure to cover all proportions of these renewable materials inblends with their fossil fuel carbon derived equivalents, as theseblends have biobased carbon fractions when measured with ASTM methodD6866.

In another embodiment, isobutanol produced by a biocatalyst from biomasscan be directly used as a gasoline replacement. In other embodiments,however, isobutanol produced in this manner is reacted as describedherein to provide a mixture of hydrocarbons which may also contain otherorganic compounds such as ethers and esters that can be used as dieselfuel. Other alcohols, for example, n-butanol and isoamyl alcohol derivedfrom biomass (e.g. by fermentation), can be similarly treated to producedifferent hydrocarbon mixtures that also meet diesel fuelspecifications. These mixtures may also contain ethers and estersderived from the starting alcohols. In general, the types of moleculessuitable for use as a diesel fuel, e.g. linear and mono-branchedalkanes, fatty acid esters, and ethers, have high cetane numbers.

In one embodiment, diesel fuel is produced from renewable isobutanol inthe following manner: 1) isobutanol produced by a biocatalyst frombiomass-derived feedstocks is removed from the fermentation broth bydistillation or other means (e.g., extraction from the fermentorheadspace under reduced pressure); 2) isobutanol of sufficient purity istransferred to a reactor containing a heterogenous catalyst thatcatalyzes the dehydration of isobutanol to form isobutylene, and one ormore of the condensation of one or more isobutylene units into a largerhydrocarbon (e.g. oligomerization), the rearrangement of the isobutylenemonomers during condensation (or the rearrangement of oligomerizedhydrocarbons), and the reaction of alkene bonds in the hydrocarbonproduct with hydrogen (e.g. hydrogenation), methanol, or carbon dioxide.The reactor containing isobutanol and the catalyst described in (2) ismaintained at an operating temperature and pressure that promotes thereactions required to convert the isobutanol into a diesel fuel, and thehydrocarbon or organic compound mixture obtained after step (and 2) isremoved from the reactor and treated to remove impurities. Thehydrocarbon or organic compound mixture or biofuel is tested againstASTM diesel fuel specifications, and if it does not meet specificationsit is blended with other biofuel components to produce material thatwill pass specifications. Similarly, renewable jet fuel can be preparedby a similar method, except that the hydrocarbons prepared in step (2)on average have a lower molecular weight and are more volatile than thehydrocarbons appropriate for renewable diesel fuel, and meet ASTMspecifications for jet fuel (in which case the mixture may be useddirectly as jet fuel, or if not, are blended with a jet fuel or jet fuelprecursor to meet the appropriate ASTM specification). Likewise,renewable gasoline (including aviation gasoline) can be prepared bysimilar method, except that the hydrocarbons prepared in step (2) have alower molecular weight and are more volatile than the hydrocarbons forrenewable jet fuel, and meet ASTM specifications for gasoline (in whichcase the mixture may be used directly as gasoline, or if not, blendedwith gasoline or a gasoline precursor to meet the appropriate ASTMspecification).

In certain embodiments, and additional aromatization step can beincorporated into the process (as described herein) to provide biofuels(e.g., gasoline, aviation gasoline, diesel, or jet fuels) whichadditionally include an aromatic component. In a particular embodiment,jet fuel is produced in the following manner: 1) isobutanol produced byfermentation of a biomass-derived feedstock is removed from thefermentation broth by distillation or other means; 2) isobutanol ofsufficient quality is transferred to a reaction zone containing acatalyst that catalyzes the dehydration of isobutanol to formisobutylene; 3) the isobutylene is oligomerized in a reaction zone toform a mixture of unsaturated aliphatic hydrocarbons suitable for jetfuel (e.g., primarily C₁₂ hydrocarbons); 4) isobutylene is reacted in areaction zone to Bolin aromatic compounds, especially p-xylene, andhydrogen gas; 5) hydrogen gas is separated from the aromatic productsand used to convert the oligomers fanned in step (3) to saturatedhydrocarbons; 6) the aliphatic and aromatic hydrocarbons are blended toa product that meets all jet fuel specifications; and optionally 7) ifthe biofuel does not meet jet fuel specifications it is blended withother biofuel or petroleum based components to produce a mixture thatmeets jet fuel specifications. Alternatively, off-specificationrenewable jet fuel can be used as diesel fuel or blended with any dieselfuel.

In several embodiments, the process described herein produces othertypes of hydrocarbon mixtures including various different grades ofdiesel fuel including diesel fuel for trucks, trains, and ships. Inother words, any hydrocarbon mixture that can be used as a fuel can beproduced from renewable alcohols by the methods described.

As described above, isobutanol is a particular embodiment of therenewable alcohol starting materials used in the process of the presentinvention. However, any C₂-C₆ alcohol formed from biomass suitable foruse in the process of the present invention. For example ethanol can bedehydrated to form ethylene, separately or in situ, and thenoligomerized to form linear hydrocarbons of various lengths.Alpha-olefins of varying size, i.e. C₄ to greater than C₂₀ are producedin this manner. If completely unbranched alkanes are desired to usedirectly as diesel fuel or to blend with other hydrocarbons to producediesel fuel, the products, i.e. alk-1-enes, of the alpha-olefin processare reduced with hydrogen to form saturated linear alkanes sized C₄ togreater than C₂₀. The oligomerization of ethylene to form thesecompounds usually requires an organometallic aluminum catalyst, butzeolite-catalyzed oligomerization has also been reported (see Accountsof Chemical Research 2005, 38, 784-793; Journal of Natural Gas Chemistry2002, 11, 79-86; U.S. Pat. No. 4,025,575; WO 2005/092821 A1).

As discussed herein, in most embodiments of the process of the presentinvention, a renewable alcohol (or mixture of renewable alcohols)derived from biomass, for example by fermentation, are dehydrated toform alkenes which are then converted to biofuels or fine chemicalsthrough one or more subsequent processing steps. The renewable alcoholmay be dehydrated by feeding an aqueous solution of the alcohol (ormixture of alcohols) into a reactor containing e.g. an acidic solidphase catalyst, which is heated to convert the alcohol into an alkene,e.g. isobutylene. In another embodiment, the alkene is captured afterthe dehydration step, separated from the water, and fed into a separateoligomerization reactor. In still another embodiment, the alkene isformed in situ in the reactor and continues to react in other ways withthe catalyst in the reactor to form oligomers that are precursors to, orare biofuels. In yet another embodiment, a mixture of renewable alcoholsis fed into a dehydration reactor to form a mixture of alkenes that arefurther oligomerized to precursors to, or to biofuels in the samereactor, or a second reactor in the process. The oligomerizationproducts are reduced to saturated hydrocarbons by hydrogen, wherein thehydrogen may be produced by the aromatization of a second stream ofrenewable alcohol or alkene. These aromatics are optionally blended withthe saturated hydrocarbons to produce biofuels, e.g. jet fuel, that meetASTM specifications.

In one embodiment of the invention described herein, a biofuelprecursor, e.g. isobutanol, formed by the fermentation of abiomass-derived feedstock is dehydrated in a chemical reactor thatcontains a solid phase catalyst that catalyzes both the dehydration,oligomerization, and partial rearrangement of the alcohol to formprecursors to, or form biofuels (e.g. jet or diesel fuels) withincreased isomer diversity, relative to a biofuel formed byoligomerization without rearrangement. The resulting alkenes are alsoreduced by the solid phase catalyst in the presence of hydrogen to formsaturated hydrocarbon biofuels (e.g. jet or diesel fuels). In order toobtain a fully renewable biofuel, the hydrogen used for thehydrogenation is derived from biofuel precursors (e.g. alkenes) that arereacted over an aromatization catalyst to form aromatics for blendinginto the biofuel, for example jet fuel. In another embodiment, a linearbiofuel precursor, e.g. n-butanol, formed by the fermentation of abiomass-derived feedstock is dehydrated in a chemical reactor thatcontains a solid phase catalyst that catalyzes both the dehydration,oligomerization, and rearrangement of the alcohol to form precursors to,or form biofuels with increased branching and isomer diversity, relativeto a biofuel formed by oligomerization without rearrangement, that arealso reduced by the solid phase catalyst in the presence of renewable ornon-renewable hydrogen to form saturated hydrocarbon biofuels, e.g. jetor diesel fuels. In some embodiments, the biofuel precursor to (e.g.alcohol) is fed to the dehydration/oligomerization/rearrangement reactoras an aqueous solution. In yet another embodiment, the biofuel precursor(e.g. alcohol) is converted into an alkene in a first reactor, then thealkene is fed into a second, separate reactor where it is oligomerizedand rearranged to form precursors to, or forms biofuels (e.g. jet ordiesel fuels) with increased branching and isomer diversity, relative toa biofuel formed by oligomerization without rearrangement, that arereduced by another solid phase catalyst in the presence of renewable ornon-renewable hydrogen in a third reactor to form saturated hydrocarbonbiofuels, e.g. jet or diesel fuels.

In a particular embodiment, the biofuel produced by the dehydration ofrenewable isobutanol (e.g., produced by fermentation), and subsequentoligomerization, rearrangement, and reduction (e.g., hydrogenation) is ajet fuel comprising a distribution of hydrogenated oligomers ofbutylenes in which a majority of the oligomers are isomers of butylenetrimers containing 12 carbon atoms. In other particular embodiments,this composition is blended with aromatics produced from renewablealcohols (e.g., the same renewable alcohols used to prepare thehydrogenated butylene oligomers).

The resulting mixture of alkanes and aromatics that is the final jetfuel product is not soluble in water. Any water that passes through thesystem, either as part of an aqueous alcohol mixture used to feed thedehydration reactor, or which is removed from the alcohol during thedehydration process, is separated from the final product by phaseseparation. Alternatively, if a separate dehydration reactor is used,water is separated from the alkene product stream by a similar method.By tuning the catalyst composition and reactor conditions it is possibleto produce a mixture of hydrocarbons that meets jet fuel specifications,wherein the primary purification of the product steam comprises removalof water and trace contaminants that interfere with its use as a fuel(e.g. by phase separation). Alternatively, additional purification maybe carried out to refine the mixture of hydrocarbons into a biofuelmeeting ASTM specifications (e.g. gasoline, diesel, or jet fuelspecifications).

In some embodiments, the product stream will comprise a mixture ofhydrocarbons which can be separated into different fractions, each ofwhich corresponds to a particular type of fuel, such that the majorityor all of the product stream can be distilled into two or threefractions corresponding to e.g. jet fuel and other fuels such asgasoline or diesel fuel. Any remaining organic material, primarilypolymeric material, can be used for other purposes such as lubricants,tars, or oils. In other embodiments, the product stream will comprise amixture of hydrocarbons that can be distilled to produce one or more ofa jet fuel, #1 grade diesel fuel, and #2 grade diesel fuel. For example,the product stream comprises a mixture of hydrocarbons that aredistilled into a jet fuel and #1 grade diesel fuel; or the productstream is distilled into a jet fuel and #2 grade diesel fuel; or theproduct stream is distilled into #1 grade diesel fuel and #2 gradediesel fuel; or the product stream is distilled into #1 grade dieselfuel, #2 grade diesel fuel, and jet fuel.

In still other embodiments after distilling the product stream intoseparate product streams comprising one or more of a jet fuel, #1 gradediesel fuel, #2 grade diesel fuel, the residual portion of the productstream comprises hydrocarbons which are blended into fuel precursors sothat the resulting blends meet all ASTM specifications for therespective fuel. For example, the residual hydrocarbon componentsremaining after distillation of one or more of a jet fuel, #1 gradediesel fuel, and/or #2 grade diesel fuel can be purified and used forother purposes, such as using residual 2,2,4-trimethylpentane as anoctane enhancer for gasoline and an additive for gasoline replacement.

In particular embodiments, a renewable jet fuel of the present inventioncomprises at least one of the following eight-carbon and twelve-carboncompounds: renewable 2,2,4-trimethylpentane, renewable2,2,4,4,6-pentamethylheptane, renewable 2-methylpentane, renewable2,4-dimethylheptane, renewable 2,4,6-trimethylnonane and renewablexylene. In another particular embodiment, the jet fuel comprises atleast two of those compounds. In another embodiment, the combinedconcentration of these compounds in the renewable jet fuel of thepresent invention is at least about 10%, at least about 50%, or at leastabout 100% greater than their concentration in petroleum-derived,non-renewable jet fuel.

In particular embodiments, a renewable diesel fuel comprises one or moreof 2,2,4-trimethylpentane, 2,2,4,4,6-pentamethylheptane,2,2,4,4,6,6,8-heptamethylnonane, 2,2,4,4,6,6,8,8,10-nonamethylundecane,and 2,2,4,4,6,6,8,8,10,10,12-undecamethyltridecane. In other particularembodiments, the renewable diesel fuel comprises oligomers that havebeen rearranged, such as 2,2,4-trimethylpentane,2,2,4,4,6-pentamethylheptane, 2,2,4,4,6,6,8-heptamethylnonane,2,2,4,4,6,6,8,8,10-nonamethylundecane, and2,2,4,4,6,6,8,8,10,10,12-undecamethyltridecane and various isomers andother derivatives of these compounds including, but not limited to,2,3,4-trimethylpentane, 2,3,4,4,5-pentamethylheptane,2,3,3,4,5,6-pentamethylheptane, and2,2,3,4,6,6,7,8,10-nonamethylundecane. In yet another embodiment, theseorganic compounds are present in concentrations such that the entiremixture is a diesel fuel that meets ASTM D975 specifications for dieselfuel as determined by ASTM methods D93, D86, D445, D613, D1319 and D130.

In most embodiments, the biofuels or biofuel precursors of the presentinvention comprise about 100% of renewable aliphatic hydrocarbons (e.g.,renewable C₈-C₂₄ branched aliphatic hydrocarbons) and optionallyaromatic hydrocarbons (e.g., renewable BTX) prepared by the processesdescribed herein. In other embodiments, the biofuels of the presentinvention comprise a blend of renewable hydrocarbons (aliphatic and/oraromatic) and non-renewable compounds (e.g., petroleum-derivedhydrocarbons, additives, etc.). In some embodiments, the biofuels orbiofuel precursors of the present invention comprise at least about 1%of renewable C₈-C₂₄ branched aliphatic hydrocarbons, or about 2%, about5%, about 10%, about 15%, about 20%, about 30%, about 40%, about 50%,about 60%, about 70%, about 80%, about 90%, about 95%, or about 99% ofrenewable C₈-C₂₄ branched aliphatic hydrocarbons.

In yet another embodiment, the biofuel precursors are a mixture ofalcohols that are ethanol, propanols, butanols, and pentanols. Themixture is oligomerized with rearrangement to form a complex productmixture of branched and unbranched hydrocarbons and other organiccompounds that are present in concentrations such that the entiremixture is a diesel fuel that meets ASTM D975 specifications for dieselfuel as determined by ASTM methods D93, D86, D445, D613, D1319 and D130.These embodiments are only exemplary since many different combinationsof alcohol biofuel precursors and degrees of rearrangement are possibleto create mixtures of branched and unbranched hydrocarbons and organiccompounds that are present in these mixtures in concentrations such thatthese mixtures are diesel fuel that meets ASTM D975 specifications fordiesel fuel as determined by ASTM methods D93, D86, D445, D613, D1319and D130.

In still other embodiments, the biofuel precursors are propanols, andthe hydrocarbon and organic compound mixture produced comprises2-methylpentane, 2,4-dimethylheptane, 2,4,6-trimethylnonane,2,4,6,8-tetramethylundecane, 2,4,6,8,10-pentamethyltridecane,2,4,6,8,10,12-hexamethylpentadecane, and2,4,6,8,10,12,14-heptamethylheptadecane and isomers and otherderivatives of these compounds in concentrations such that the entiremixture is a jet fuel that also meets ASTM D975 specifications fordiesel fuel as determined by ASTM methods D93, D86, D445, D613, D1319and D130. In yet another embodiment, the biofuel precursors arepentanols and the hydrocarbon and organic compound mixture producedcomprises 1,3-diisopropylbutane, 1,3,5-triisopropylhexane,1,3,5,7-tetraisopropyloctane, and 1,3,5,7,9-pentaisopropyldecane andisomers and other derivatives of these compounds in concentrations suchthat the entire mixture is a jet fuel that also meets ASTM D975specifications for diesel fuel as determined by ASTM methods D93, D86,D445, D613, D1319 and D130.

As discussed above, many fine chemicals such as acrylates or phthalatesare conventionally prepared from petroleum-based starting materials.Renewable alcohols can also serve as starting materials for preparingrenewable fine chemicals. For example, acrolein or methacrolein can beprepared by oxidizing propylene and isobutylene, alkanes such asisobutane, and alcohols such as t-butanol or isobutanol by partialoxidation over a suitable catalyst. Some processes generate acrolein ormethacrolein in the first step, which is then oxidized to acrylic acidor methacrylic acid in a second step, and converted into a methylester—the monomeric unit for polymerization—in a third step. (U.S. Pat.Nos. 3,301,906, 3,825,502, 3,755,458, 4,129,600, 4,190,608, 4,354,044).Alternatively, such compounds can be prepared in a two step process inwhich the appropriate alkene is oxidized to acrolein or methacrolein andthen methyl acrylate or methyl methacrylate is prepared by oxidativeesterification (U.S. Pat. No. 5,969,178). Generally, the same reactionconditions can be used to prepare alkacroleins and alkacrylates (e.g.,wherein the “alk” moiety refers to an alkyl radical such as methyl,ethyl, etc.) from higher molecular weight alkenes and alcohols. Forexample, 2-methyl-1-butene and 2-methyl-1-butanol reacted under theseconditions to provide ethacrolein and ethacrylates. Thus, in someembodiments, renewable acrylates such as renewable acrolein,methacrolein, ethacrolein, acrylic acid, methacrylic acid, ethacrylicacid, acrylic asters, methacrylic esters, and ethacrylic esters can beprepared by the oxidation of the appropriate renewable alcohol,renewable alkene (e.g. prepared from the corresponding renewable alcoholby dehydration, or by a combination of dehydration, andoligomerization), or renewable alkane (e.g. prepared from thecorresponding renewable alkene by hydrogenation), optionally in thepresence of alcohol (renewable or non-renewable alcohols) if an ester isthe desired product. In other embodiments, the alkalcroleins oralkacrylates can be prepared by direct oxidation of appropriaterenewable alcohols prepared e.g., by fermentation of biomass asdescribed herein. One advantage of direct oxidation of alcohols is thatthe dehydration of the alcohol on the oxidation catalyst provides steamto regenerate the catalyst during operation, increasing catalystlifetime and allowing the reactor to operate longer without interruptionto regenerate.

As indicated above, aromatic fine chemicals are conventionally preparedfrom aromatic starting materials distilled from, or derived frompetroleum. As discussed herein, renewable aromatic compounds can also beprepared from renewable alcohols, for example by aromatization ofalkenes or alkanes prepared by dehydration or dehydration andhydrogenation of renewable alcohols. Alternatively, renewable aromaticcompounds can be obtained by alkylation of renewable aromatic compoundswith renewable alkenes, and other processes described herein.

In one embodiment, a renewable alcohol, e.g. isobutanol, is dehydratedover an acidic catalyst in a reactor to form isobutylene. Theisobutylene is recovered and reacted under the appropriate high heat andpressure conditions in a second reactor containing a catalyst known toaromatize aliphatic hydrocarbons, as described herein. The renewablep-xylene is recovered and may be shown to be renewable by ASTM methodsreferenced herein. In another embodiment, the renewable alcohol, e.g.isobutanol is dehydrated and dimerized over an acid catalyst; theresulting diisobutylene is recovered and reacted in a second reactor toform renewable p-xylene. In yet another embodiment, a renewable alcohol,e.g. isobutanol containing up to 15% water is dehydrated, or dehydratedand oligomerized, and the resulting oligomers aromatized to formrenewable p-xylene. In still another embodiment, hydrogen and C₁-C₃hydrocarbon byproducts of the aromatization reaction are recovered forlater use in other reactions. In yet another embodiment, the dehydrationof the renewable alcohol and the aromatization of the resulting alkeneoccurs in a single reactor using a single catalyst, to faun a mixture ofrenewable aromatic compounds. The resulting renewable aromatic compoundsare purified, e.g. by distillation or crystallization to obtain purestreams of individual renewable aromatic products. The pure xylenes fromthese reactions are oxidized to their corresponding phthalic acids andphthalate esters using the methods described herein.

In other embodiments, the alcohol is renewable 1-propanol or 2-propanol,which is dehydrated or dehydrated and oligomerized over an acid catalystand then reacted over a second catalyst to produce benzene, toluene, andxylenes in addition to hydrogen and C₁-C₃ hydrocarbons. In yet otherembodiments, the renewable alcohols are C₄ alcohols such as 1-butanoland 2-butanol, C₅ alcohols such as isopentanol and 2-pentanol, or C₆alcohols such as isohexanol and 2-hexanol, that are dehydrated, ordehydrated and oligomerized, and then reacted over a second catalyst toproduce xylenes and other alkyl- and dialkyl-benzenes in addition tohydrogen and C₁-C₃ hydrocarbons. In still another embodiment, thearomatization of the renewable alcohols described above is carried outin a single reactor. In yet another embodiment, the renewable alcoholscontain up to saturating levels of water, and the resulting renewablearomatic compounds are purified to obtain pure streams of individualrenewable aromatic products. The pure xylenes from these reactions arethen oxidized to their corresponding phthalic acids and phthalate estersusing the methods described herein.

In other embodiments, mixtures of C₂-C₁₀ alcohols and/or C₂-C₂₀hydrocarbons produced by the thermochemical processing of biomass aretreated over appropriate catalysts to form renewable aromatic compoundsand hydrogen and C₁-C₃ hydrocarbons. The renewable aromatic compoundsare purified to obtain pure streams of individual renewable aromaticproducts. The pure xylenes from these reactions are oxidized to theircorresponding phthalic acids and phthalate esters using the methodsdescribed above.

EXAMPLES Example 1 Isobutanol Fermentation

An overnight culture was started in a 250 mL Erlenmeyer flask withmicroorganism from a freezer stock (e.g., Escherichia coli modified toproduce isobutanol) with a 40 mL volume of modified M9 medium consistingof 85 g/L glucose, 20 g/L yeast extract, 20 μM ferric citrate, 5.72 mg/LH₃BO₃, 3.62 mg/L MnCl₂.4H₂O, 0.444 mg/L ZnSO₄.7H₂O, 0.78 mg/LNa₂MnO₄.2H₂O, 0.158 mg/L CuSO₄.5H₂O, 0.0988 mg/L CoCl₂.6H₂O, 6.0 g/LNaHPO₄, 3.0 g/L KH₂PO₄, 0.5 g/L NaCl, 2.0 g/L NH₄Cl, 0.0444 g/L MgSO₄,and 0.00481 g/L CaCl₂ and at a culture OD₆₀₀ of 0.02 to 0.05. Thestarter culture was grown for approximately 14 hrs in a 30° C. shaker at250 rpm. Some of the starter culture was then transferred to a 400 mLDasGip fermentor vessel containing about 200 mL of modified M9 medium toachieve an initial culture OD₆₀₀ of about 0.1. The vessel was attachedto a computer control system to monitor and control the fermentation toa pH of 6.5 (by appropriate addition of base), a temperature of 30° C.,dissolved oxygen levels, and agitation. The vessel was agitated, with aminimum agitation of 200 rpm—the agitation was varied to maintain adissolved oxygen content of about 50% of saturation using a 12 sl/h airsparge until the OD₆₀₀ was about 1.0. The vessel was then induced with0.1 mM IPTG. After continuing growth for approximately 8-10 hrs, thedissolved oxygen content was decreased to 5% of saturation with 200 rpmminimum agitation and 2.5 sl/h airflow. Continuous measurement of thefermentor vessel off-gas by GC-MS analysis was performed for oxygen,isobutanol, ethanol, carbon dioxide, and nitrogen throughout theexperiment. Samples were aseptically removed from the fermentor vesselthroughout the fermentation and used to measure OD₆₀₀, glucoseconcentration, and isobutanol concentration in the broth. Isobutanolproduction reached a maximum at around 21.5 hrs with a titer of 18 g/Land a yield of approximately 70% maximum theoretical. The broth wassubjected to vacuum distillation to provide a 84:16 isobutanol/watermixture which was redistilled as needed to provide dry isobutanol.

Example 2 Isobutanol Dehydration

23 g of a commercial γ-alumina catalyst was loaded into a fixed-bedtubular reactor. Wet isobutanol containing about 12% water was fedthrough a preheater and onto the catalyst bed. The internal reactortemperature was maintained at 310° C., and the WHSV of the isobutanolwas ˜6 hr⁻¹. Isobutylene and water containing about <1% of unreactedisobutanol were recovered. The products were separated in a gas-liquidseparator and the isobutylene recovered. The conversion was >99%, andGC-MS analysis of the gas phase effluent indicated it was >90%isobutylene with the remainder comprising linear butenes.

Example 3 Isobutanol Dehydration

20 mL of wet isobutanol containing 15% water was reacted in a batchreactor over 2 gm of Zeolite-Y CBV-780 at 220° C. The reactor pressureincreased from atmospheric pressure to 350 psig. Conversion ofisobutanol was about 25% and GC-MS analysis indicated the productmixture was >90% isobutylene and <10% linear butenes.

Example 4 Isobutanol/Gasoline Blend

Isobutanol was blended with 84.7 octane gasoline with a Reid vaporpressure (RVP) of 8.47 psi to a concentration of 12.5% v/visobutanol/gasoline. The RVP of the blend was 8.14 psi and the octanenumber was 86.9.

Example 5 n-Butanol/Gasoline Blend

N-butanol is blended with 84.7 octane gasoline with a Reid vaporpressure of 8.47 psi to a concentration of 12.5% v/v n-butanol/gasoline.The RVP of the blend is 8.14 psi and the octane number is 85.0.

Example 6 Pentanol/Gasoline Blend

Pentanols produced by a fermentation process similar to that describedin Example 1 (except that a microorganism preferentially producingpentanols instead of isobutanol was used) are separated from thefermentation broth by distillation. The pentanols are blended with 84.7octane gasoline with a Reid vapor pressure of 8.47 psi to aconcentration of 12.5% v/v pentanols/gasoline. The resulting blend istested and shown to meet ASTM specifications for gasoline. The RVP ofthe blend is 8.0 psi and the octane number is 85.0.

Example 7 Isobutanol/Gasoline Blend

Isobutanol prepared by a fermentation process e.g., of Example 1 wasblended with 84.7 octane gasoline with a Reid vapor pressure of 8.47 psito a concentration of 16.1% v/v isobutanol/gasoline. The RVP of theblend was 7.98 psi and the octane number was 87.7.

Example 8 Thermochemical Synthesis of C₁-C₇ Alcohols

Poplar wood chips are heated for 8 hours in a gasifier at 500° C. over asolid catalyst comprising cobalt and sodium to produce a mixture ofalcohols including methanol, ethanol, propanols, butanols, pentanols,hexanols, and heptanols. The butanols and pentanols are separated fromthe mixture by distillation and are blended with 84 octane gasoline witha vapor pressure of 15 psi at 100° F. to a concentration of 20% v/valcohols in gasoline. The resulting blend is tested and shown to meetASTM specifications for gasoline. The vapor pressure of the blend is12.5 psi at 100° F. and the octane number is 84.6. Using ASTM methodD6866 it is determined that the blend is renewable. A life cycleanalysis of the production of the blend is performed to show thatburning a gallon of the blend produces less than 19 pounds of net carbondioxide. The cost of producing a gallon of the blend is shown to beequivalent to the cost of a gallon of unblended gasoline.

Example 9 Diisobutylene from Isobutanol in an Integrated Flow Reactor

Isobutanol produced by fermentation (e.g. according to Example 1) wasseparated from the fermentation broth by distillation. The isobutanol,which contains 16% water, was passed through a chemical reactorcontaining a commercial γ-alumina catalyst heated to 310° C. at ˜10 psigand a WHSV of 6 hr⁻¹. The water drained from the bottom of the reactorcontained less than 0.1 M isobutanol, and isobutylene (gas) wascollected with >99% conversion. The isobutylene gas was dried by passingit through molecular sieves, and was then fed into a second reactorcontaining a ZSM-5 catalyst maintained at 140-160° C., ambient pressure,and WHSV=1.5 hr⁻¹ to give ˜60% conversion to a mixture of about 80% ofdiisobutylene isomers and about 20% triisobutylene isomers and minorquantities of higher molecular weight products.

Example 10 Isododecane from Isobutanol in an Integrated Flow Reactor

Isobutanol produced by fermentation (e.g. according to Example 1) wasseparated from the fermentation broth by distillation. The isobutanol,which contains 16% water, was passed through a chemical reactorcontaining acidic commercial γ-alumina catalyst heated to 310° C. at ˜10psig and a WHSV of 6 hr⁻¹. The water drained from the bottom of thereactor contained less than 0.1 M isobutanol, and isobutylene (gas) wascollected with >99% conversion. The isobutylene gas was dried by passingit through molecular sieves, and was then fed into a second reactorcontaining Amberlyst® 35, maintained at 100-120° C., ambient pressure,and WHSV=2.5 hr⁻¹ to give ˜90% conversion to a mixture of about 15% ofdiisobutylene isomers, 75% triisobutylene isomers and 10% tetramers. Theliquid product was pumped to a trickle-bed hydrogenation reactor packedwith a commercial 0.5% Pd on alumina catalyst and co-fed with 10% excesshydrogen. Hydrogenation of >99% of the olefins occurred at 150° C., 150psig, and WHSV=3 hr⁻¹. The saturated hydrocarbon product was collectedwith an overall process yield of ˜90%.

Example 11 Gasoline from Dimers and Trimers of Isobutylene

The product mixture from Example 9 was fed into a hydrogenation reactorcontaining a 0.5% Pd on alumina catalyst maintained at 150° C. and 150psi to give a saturated hydrocarbon product, which was distilled atatmospheric pressure to give three fractions containing diisobutylene,triisobutylene and small quantities of higher molecular weight products.The three fractions can be separated and used in aviation gasoline andauto gasoline.

Example 12 Methylundecene Isomers from Isobutylene

90 g of isobutylene, as formed in Example 2, was loaded into a 350 mLbatch reactor with 10 g of a ZSM-5 catalyst (Si:Al ratio=80) that hadbeen treated with 2,4,6-trimethyl pyridine. The sealed reactor washeated to 220° C. and allowed to react for approximately 40 hours. 75 mLof product was collected and a sample was analyzed by GC/MS. Thecomposition was approximately 30% C₁₂ or larger molecules and theprimary compounds were isomers of methylundecene.

Example 13 Methylundecene Isomers to Diesel Fuel

The unsaturated product from Example 12 was loaded into a 350 mL batchreactor containing 1 g of 5% Pd/C catalyst. The reactor was flushed withnitrogen and pressurized with 200 psig of hydrogen. The reactor washeated to 100° C. and held at this temperature for 1 hour. 70 mL ofproduct was collected and analyzed by GC/MS. The product was found to befully saturated. 70 mL of this hydrogenated mixture was then distilledto concentrate the C₁₂+ fraction (i.e., the fraction containing C₁₂ orhigher hydrocarbons). Approximately 50 mL of the mixture was distilledoff (primarily C₈ hydrocarbons), leaving 20 mL of C₁₂+ hydrocarbons. Theflash point of the final product was measured as 51° C. and the derivedcetane number was measured by ASTM D6890-07 as 68. The product wasdetermined to meet the ASTM specifications for #1 diesel fuel.

Example 14 Diesel Fuel Blend Composition

The renewable #1 diesel fuel from Example 13 is blended in a 50:50mixture with #2 diesel fuel having a flash point of 62° C. and a cetanenumber of 44. The resulting blend is tested and shown to meet ASTMD975-07 specifications for #2 diesel fuel. The flash point of the blendis 55° C. and the derived cetane number is 56 using ASTM methodD6890-07. It is determined that the blend is renewable (i.e., meets therequirements of ASTM method D6866).

Example 15 Jet Fuel from Isobutylene

The trimerization of isobutylene (e.g., isobutylene prepared asdescribed in Examples 1 or 2) was carried out using a fixed bedcontinuous flow system equipped with a tube furnace housing SS 316reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, a backpressure regulator, and a gas-liquid separator. In a typicaltrimerization procedure, the reactor was loaded with β Zeolite CP 814C(Zeolyst International) and isobutylene was fed at WHSV 1-3 h⁻¹ at areaction temperature of 140-180° C., at atmospheric pressure. Theisobutylene conversion was 85% with a product distribution of about 29%dimer isomers, 58% trimer isomers, and 11% tetramer isomers. Thehydrogenation of the resulting oligomer blend was carried out at 150° C.and 150 psi H₂ to give a hydrocarbon product which was fractionated toprovide a blend of saturated C₁₂ (trimers) and C₁₆ (tetramers)hydrocarbons that were used as a jet fuel feedstock.

Example 16 Additives in a Jet Fuel Composition

To the diesel fuel produced in Example 15, dinonylnaphthylsulfonic acidis added to enhance static charge dissipation, and 10% ofpetrochemically-derived C10+ aromatics are added to improve sealperformance in older jet turbine engines. The resulting fuelcomposition, when tested using ASTM methods D56, D86, D1298, D7154,D445, D4809, D1322, D1840, D1319, D3241, D381, D3242, and D130 is shownto meet the requirements for jet fuel.

Example 17 Xylene from Diisobutylene

Diisobutylene prepared from isobutanol as described in Example 9 was fedto a reactor containing a chromium doped eta-alumina catalyst. Thereactor was maintained at 550° C. with a WHSV of 1.1 hr⁻¹. The reactionproduct was condensed and analyzed by GC-MS. The yield of the xylenefraction was about 20%, and p-xylene was produced with a selectivity of90%. Hydrogen, methane, ethane, ethylene, propane, isobutylene,n-butane, isobutylene, and 2-butene were also produced and captured foruse in other processes.

Example 18 BTEX from Isobutylene

A fixed bed continuous flow system equipped with a tube furnace housingSS 316 reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, backpressure regulator, and a gas-liquid separator was loaded with ZSM-5 CBV8014 Zeolite catalyst. The catalyst was calcined at 540° C. under N₂ for8 hrs before the reaction was started. Isobutylene (e.g., prepared asdescribed herein) was fed into the reactor at WHSV 1.0 h⁻¹ and thereaction conditions were maintained at 400-550° C. and atmosphericpressure. Aromatic products were formed in about 45% yield and theselectivity for BTEX (i.e., benzene, toluene, ethylbenzene and xylene)was 80%. The aromatic product was separated and used in fuels and otherproducts.

Example 19 BTEX from Isobutylene

A fixed bed continuous flow system equipped with a tube furnace housingSS 316 reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, backpressure regulator, and a gas-liquid separator was loaded with ZSM-5 CBV5524 G Zeolite catalyst. The catalyst was calcined at 540° C. under N₂for 8 hrs before the reaction was started. Isobutylene (e.g., preparedas described herein) was fed into the reactor at WHSV 1.0 h⁻¹ while thereaction conditions were maintained at 400-550° C. and atmosphericpressure. Aromatic products were formed in about 35% yield and theselectivity for BTEX was 80%. The aromatic product was separated andused in fuels and other products.

Example 20 BTEX from Isobutylene

A fixed bed continuous flow system equipped with a tube furnace housingSS 316 reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, backpressure regulator, and a gas-liquid separator was loaded with type YCBV870 Zeolite catalyst. The catalyst was calcined at 540° C. under N₂ for8 hrs before the reaction was started. Isobutylene (e.g., prepared asdescribed herein) was fed at WHSV 1.0 h⁻¹ while the reaction conditionswere maintained at 400-550° C. and atmospheric pressure. Aromaticproducts were formed in about 25% yield and the selectivity for BTEX was80%. The aromatic product was separated and used in fuels and otherproducts.

Example 21 Dehydration of Propanol

Propanols produced by fermentation (e.g., similar to the method ofExample 1, except that the microorganisms preferentially producepropanols rather than isobutanol) are separated from the fermentationbroth by distillation. 23 g of a commercial γ-alumina catalyst is loadedinto a fixed-bed tubular reactor. Propanol is fed through a preheaterand onto the catalyst bed. The internal reactor temperature ismaintained at 350° C., and the WHSV of the propanol is ˜6 hr⁻¹.Propylene and water are recovered, and the water contains about 7% ofunreacted propanol. The propylene and water are separated in agas-liquid separator and the propylene is recovered. The conversion isabout 90%, and GC-MS analysis of the gas phase effluent indicated itis >90% propylene.

Example 22 Diesel Fuel from Propylene

90 g of propylene, prepared as described in Example 21, is loaded into a350 mL batch reactor containing 10 g of a ZSM-5 catalyst (Si:Al ratio=80) that is been treated with 2,4,6-trimethyl pyridine. The sealedbatch reactor is heated to 220° C. and allowed to react forapproximately 40 hours. 75 mL of product is collected and a sample isanalyzed by GC/MS. The composition is approximately 30% C₁₂ or largermolecules and the primary compounds are isomers of methylundecene. Theproduct is then loaded into a 350 mL batch reactor with 1 g of 0.5% Pd/Ccatalyst. The reactor is flushed with nitrogen and pressurized with 200psig of hydrogen and heated to 100° C. and held at that temperature for1 hour, with stirring. 70 mL of product is collected and analyzed byGC/MS. The product is found to be fully saturated. 70 mL of thishydrogenated mixture is then distilled, to concentrate the C₁₂+fraction.Approximately 50 mL of the mixture is distilled off (primarily C₉compounds), leaving 20 mL of C₁₂+hydrocarbons. The flash point of thefinal product is measured as 51° C. and the derived cetane number ismeasured as 68. The product is determined to meet the ASTMspecifications for #1 diesel fuel.

Example 23 Mixed Butenes from 1-Butanol

1-Butanol produced by fermentation (e.g., similar to the method ofExample 1, except that the microorganisms preferentially produce1-butanol rather than isobutanol) is separated from the fermentationbroth by distillation. 23 g of a commercial γ-alumina catalyst is loadedinto a fixed-bed tubular reactor. 1-Butanol is fed through a preheaterand onto the catalyst bed. The internal reactor temperature ismaintained at 350° C. and the WHSV of the 1-butanol is ˜6 hr⁻¹. Butyleneisomers and water are recovered, and the water contains about 7% ofunreacted 1-butanol. The products are separated in a gas-liquidseparator and the butylene is recovered. The conversion is about 98%,and GC-MS analysis of the gas phase effluent indicated it is >90%butylene isomers.

Example 24 Diesel Fuel from Butylene

90 g of butylene, prepared as described in Example 23, was loaded into a350 mL batch reactor with 10 g of a ZSM-5 catalyst (Si:Al ratio=80) thathad been treated with 2,4,6-trimethyl pyridine. The sealed batch reactorwas heated to 220° C. and allowed to react for approximately 40 hours.75 mL of product was collected and a sample was analyzed by GC/MS. Thecomposition was approximately 30% C12 or larger molecules (C16+) and theprimary compounds were isomers of methylundecene. The product was thenloaded into a 350 mL batch reactor with 1 g of 0.5% Pd/C catalyst. Thereactor was flushed with nitrogen and pressurized with 200 psig ofhydrogen, then heated to 100° C. and held at that temperature for 1hour. 70 mL of product was collected and analyzed by GC/MS. The productwas found to be fully saturated. 70 mL of this hydrogenated mixture wasthen distilled to concentrate the C12+fraction. Approximately 50 mL ofthe mixture was distilled off (primarily C8 compounds), leaving 20 mL ofC12+hydrocarbons. The flash point of the final product was measured as51° C. and the derived cetane number was measured as 68. The fuel wasdetermined to meet the ASTM specifications for #1 diesel fuel.

Example 25 BTEX from Butylene Isomers

A fixed bed continuous flow system equipped with a tube furnace housingSS 316 reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, backpressure regulator, and a gas-liquid separator was loaded with ZSM-5 CBV8014 Zeolite catalyst. The catalyst was calcined at 540° C. under N₂ for8 hrs before the reaction was started. Butylene (e.g. prepared asdescribed in Example 24) was fed at WHSV 1.0 h⁻¹ while the reactionconditions were maintained at 400-550° C. and atmospheric pressure.Aromatic products were formed in about 40% yield and with a selectivityfor BTEX of about 80%. The aromatic product was separated and used infuels and other products.

Example 26 Jet Fuel from Propylene

The oligomerization of propylene (e.g., prepared as described in Example21) is carried out using a fixed bed continuous flow system equippedwith a tube furnace housing a SS 316 reactor (OD 5/16in×12 in), gas flowmeters, an HPLC pump, a back pressure regulator, and a gas-liquidseparator. In a typical trimerization procedure, the reactor is loadedwith β Zeolite CP 814C (Zeolyst International) and propylene is fed intothe reactor at WHSV 1-3 hr⁻¹ while the reaction conditions aremaintained at 140-180° C. and atmospheric pressure. The hydrogenation ofthe resulting blend of olefin oligomers is carried out at 150° C. and150 psi H₂ to provide a mixture of saturated hydrocarbons which aresubsequently fractionated to provide an isolated blend of about 20%dimers, 40% trimers and 40% tetramers (and trace amounts of higheroligomers) that are separated and used as a jet fuel feedstock.

Example 27 Additives for Jet Fuel Composition

To the biofuel produced in Example 26 dinonylnaphthylsulfonic acid isadded to enhance static charge dissipation, and 10% ofpetrochemically-derived aromatics are added to improve seal performancein older jet turbine engines. This composition, when tested using ASTMmethods D56, D86, D1298, D7154, D445, D4809, D1322, D1840, D1319, D3241,D381, D3242, and D130, meets the ASTM specifications for jet fuel.

Example 28

Dinonylnaphthylsulfonic acid is added to the jet fuel prepared asdescribed in Example 26 to enhance static charge dissipation andde-icing properties, but additional aromatic additives are not requiredbecause the fuel is compatible with newer, high-technology sealelastomers. This aviation biofuel composition exhibits a freezing pointof −75° C. with no cloudiness until −59° C. according to test methodASTM D2386, and when tested using ASTM methods D56, D86, D1298, D445,D4809, D1322, D1840, D1319, D3241, D381, D3242, and D130, and meets theASTM specifications for jet fuel.

Example 29 Diesel Fuel from Ethanol

Ethanol recovered from the fermentation of a carbohydrate feedstock orthe thermochemical treatment of biomass is converted into ethylene byreacting it over an HZSM-5 acidic zeolite catalyst for 2 seconds at 350°C. in a tubular flow reactor. The ethylene that is produced is separatedby flash distillation from the water by-product and passed through areactor containing 0.01% (w/w ethylene) dichloroethylaluminum.Initially, the reaction temperature is about 30° C., but the reactiontemperature increases as the exothermic reaction proceeds. A mixture ofC₆ to C₂₀ α-olefins is produced from the reaction. These olefins arerecovered and reduced with hydrogen over a platinum catalyst to formlinear saturated hydrocarbons that are blended with other hydrocarbonsto provide a composition meeting ASTM specifications for diesel fuel.

Example 30 BTEX from C₁ to C₇ Alcohols

Poplar wood chips are heated for 8 hours in a gasifier at 500° C. over asolid catalyst containing cobalt and sodium to produce a mixture ofalcohols including methanol, ethanol, propanols, butanols, pentanols,hexanols, and heptanols. A fixed bed continuous flow system equippedwith a tube furnace housing SS 316 reactor (OD 5/16 in×12 in), gas flowmeters, an HPLC pump, a back pressure regulator, and a gas-liquidseparator is loaded with ZSM-5 Zeolite catalyst. The catalyst iscalcined at 540° C. under N₂ for 8 hrs before the reaction is started.The C₁ to C₇ alcohol mixture, above, is fed into the reactor at WHSV 1.0h⁻¹ and the reaction conditions are maintained at 400-550° C. andatmospheric pressure. Aromatic products are formed in about 40% yieldand with a selectivity for BTEX of about 80%. The aromatic product isseparated and used in fuels and other products. The aromatics are testedusing ASTM method D6866 and determined to be renewable. The aromaticsare blended with gasoline and with jet fuel providing fuel blends whichare also tested using ASTM method D6866 and shown to be renewable.

Example 31 Isopentene from Isopentanol

Isopentanol produced by a fermentation process similar to that describedin Example 1 (except that a microorganism preferentially producingisopentanol instead of isobutanol was used) is separated from thefermentation broth by distillation. 23 g of a commercial γ-aluminacatalyst is loaded into a fixed-bed tubular reactor and isopentanol isfed through a preheater and onto the catalyst bed. The internal reactortemperature is maintained at 350° C., and the WHSV of the isopentanol is˜6 h⁻¹. Isopentene and water containing about 7% of unreactedisopentanol is recovered. The products are separated in a gas-liquidseparator and the dehydrated isopentene is recovered. The conversion isabout 98%, and GC-MS analysis of the gas phase effluent indicates itis >90% isopentene.

Example 32 Jet Fuel from Isopentene

The oligomerization of isopentene is carried out using a fixed bedcontinuous flow system equipped with a tube furnace housing a SS 316reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, a backpressure regulator, and a gas-liquid separator. In a typicaltrimerization procedure, the reactor is loaded with β Zeolite CP 814C(Zeolyst International) and isopentene is fed into the reactor at WHSV1-3 h⁻¹ while the reaction conditions are maintained at 100-150° C. andambient pressure. The conversion is about 85%, with a productdistribution of about 15% isopentene, 25% isopentene dimers, 50%isopentene trimers, and 10% isopentene tetramers. The hydrogenation ofthis oligomer blend is carried out at 150° C. and 150 psi H₂ to give asaturated hydrocarbon product which is fractionated to provide isolatedC₁₅ isomers that are used as a jet fuel feedstock.

Example 33 Diesel Fuel from Isopentene

90 g of isopentene, prepared as described in Example 31, is loaded intoa 350 mL batch reactor with 10 g of a ZSM-5 catalyst (Si:Al ratio=80)that is treated with 2,4,6-trimethyl pyridine. The sealed batch reactoris heated to 220° C. and the reaction is allowed to proceed forapproximately 40 hours. 75 mL of product is collected and a sample isanalyzed by GC/MS. The product composition is approximately 30% C₁₀ orlarger molecules and the primary compounds are isomers ofmethyltetradecene. The product is loaded into a 350 mL batch reactorwith 1 g of 0.5% Pd/C catalyst, the reactor is flushed with nitrogen andthen pressurized with 200 psig of hydrogen and stirred. The reactor isheated to 100° C. and held at that temperature for 1 hour. 70 mL ofproduct is collected and analyzed by GC/MS. The product is found to befully saturated. 70 mL of this hydrogenated mixture is then distilled,to concentrate the C₁₅+fraction. Approximately 50 mL of the mixture isdistilled off (primarily C₁₀ compounds), leaving 20 mL of C₁₅+hydrocarbons. The flash point of the final product is measured as 54-56°C., and the derived cetane number is 68. The final product wasdetermined to meet the ASTM specification for #2 diesel fuel.

Example 34 Dimers and Trimers of Isopentene from Isopentanol

Isopentanol produced by a fermentation process similar to that describedin Example 1 (except that a microorganism preferentially producingisopentanol instead of isobutanol was used) is separated from thefermentation broth by distillation. The isopentanol, which contains 5%water, is passed through a chemical reactor containing gamma aluminaheated to 350° C. at 1 atmosphere. Water is drained from the bottom ofthe reactor and isopentene is collected with 98% conversion. Theisopentene gas is dried by passing it through molecular sieves and isthen fed into a second reactor containing a ZSM-5 catalyst at 160° C.and 100 psi pressure to give a mixture of about 80% of pentene dimersand about 20% of pentene trimers and minor quantities of highermolecular weight products at 80% conversion.

Example 35 Gasoline from Dimers of Isopentene

The product mixture from Example 34 is charged into a hydrogenationreactor with a 0.5% Pt on alumina catalyst, and which is maintained at150° C. and 150 psi hydrogen to give a saturated hydrocarbon product,which was distilled at atmospheric pressure to give three fractionscontaining C₁₀ isomers, C₁₅ isomers, and small amounts of C₂₀ isomersand traces of higher molecular weight products, respectively. Thefractions are separated and blended in gasoline.

Example 36 BTEX from Isopentene

A fixed bed continuous flow system equipped with a tube furnace housingSS 316 reactor (OD 5/16in×12 in), gas flow meters, an HPLC pump, a backpressure regulator, and a gas-liquid separator is loaded with ZSM-5 CBV8014 Zeolite catalyst. The catalyst is calcined at 540° C. under N₂ for8 hrs before the reaction is started. Isopentene (e.g., as prepared inExample 31) is fed into the reactor at WHSV 1.0 h⁻¹ while the reactorconditions are maintained at 400-550° C. and atmospheric pressure.Aromatic products are formed in about 40% yield and with a selectivityfor BTEX of about 80%. The aromatic product is separated and used infuels and other products.

Example 37 Experimental Jet Fuels

Renewable jet fuels are produced from biofuel precursors such asisobutanol by reacting the precursors in chemical reactor(s), asdescribed above, containing a catalyst that converts the precursors intomixtures of hydrocarbons. The resulting fuel product meets thespecifications for jet fuel.

If the biofuel precursor is isobutanol, then the renewable jet fuelcomposition will comprise branched C₈, C₁₂ and C₁₆ hydrocarbons. In thisexample, experimental jet fuel blends were prepared with only C₈, C₁₂and C₁₆ hydrocarbons to better understand the impact of chemicalcomposition on key physical properties. Various experimental jet fuelblends and the physical properties of these blends are provided below inTable 1.

TABLE 1 Experimental Jet Fuel Blends and Physical Properties PhysicalProperties Flash Freezing Smoke Density Matrix Blend Composition vol %Point Point Point (Kg/L) at Aromatics C₈ i-paraffin p- (° C.) (° C.)(mm) 15.6° C. Blend vol % vol % vol % xylene n-C₈ i-C₈ n-C₁₂ i-C₁₂ n-C₁₆i-C₁₆ Min 38 Max −40 Min 25 775-840 1 5 10 95 5.0 0.5 9.0 3.8 72.2 0.59.0 26 −58.0 32 755 2 5 10 75 5.0 2.4 7.1 19.0 57.0 2.4 7.1 28 −36.5 33753 3 5 2 95 5.0 0.1 1.8 4.1 78.6 0.5 9.8 38 −58.5 32 758 4 5 2 75 5.00.5 1.4 20.7 62.1 2.6 7.8 38 −36.0 33 757 5 10 10 95 10.0 0.5 8.6 3.668.4 0.5 8.6 26 −58.0 24 765 6 10 10 75 10.0 2.3 6.8 18.0 54.0 2.3 6.828 −38.5 30 756 7 10 2 95 10.0 0.1 1.7 3.9 74.5 0.5 9.3 36 −56.0 28 7638 10 2 75 10.0 0.5 1.4 19.6 58.8 2.5 7.4 38 −38.0 30 763 9 15 10 95 15.00.4 8.1 3.4 64.6 0.4 8.1 26 −58.5 24 765 10 15 10 75 15.0 2.1 6.4 17.051.0 2.1 6.4 28 −38.0 23 765 11 15 2 95 15.0 0.1 1.6 3.7 70.3 0.5 8.8 34−54.5 22 776 12 15 2 75 15.0 0.4 1.3 18.5 55.5 2.3 6.9 36 −38.0 24 768

Example 38 Isooctene from Isobutylene/SPA Catalyst

A fixed bed continuous flow reactor was loaded with solid phosphoricacid (SPA) catalyst. The SPA catalyst was prepared according topublished procedures (Ind. Eng. Chem. Res. 2007, 46,7838-7843) and wascalcined at 320° C. and was sieved to obtain 2-3 mm particles.Isobutylene was fed into the reactor at a WHSV between 1.0-1.3 h⁻¹ withreaction conditions maintained at 160-180° C. and atmospheric pressure.The isobutylene was converted to liquid oligomers at about 90% yield andthe selectivity for isooctene isomers was 82%. The isooctene isomerswere separated from heavier oligomers by fractionation at atmosphericpressure. The isooctene isomers were hydrogenated to isooctane asdescribed in the hydrogenation step in Example 23. The octane valueR+M/2 of the hydrogenated isooctane was 98, the vapor pressure RVP was1.65 psig, and the freezing point was below −55° C.

Example 39 Isooctene from Isobutylene/Zeolite ZSM-5 Catalyst

A fixed bed continuous flow reactor was loaded with ZSM-5 CBV 2314Zeolite catalyst. Prior to reaction, the catalyst was calcined at 540°C. under N₂ for 8 hrs. Isobutylene was fed into the reactor at a WHSVbetween 1.2-2 h⁻¹ and the reaction conditions were maintained at160-180° C. and atmospheric pressure. The isobutylene was converted toliquid oligomers at about 85% yield, and the selectivity for isoocteneisomers was 88%. The isooctene isomers were separated from heavieroligomers by atmospheric fractionation. The isooctene isomers werehydrogenated to isooctane as described in the hydrogenation step inExample 23. The octane value R+M/2 of the hydrogenated isooctane was 98,vapor pressure RVP was 1.65 psig, and freezing point was below −55° C.

Example 40 Isooctene from Isobutylene/Amberlyst-15 Catalyst

3 grams of dry Amberlyst 15 catalyst was charged into a 300 mL stainlesssteel batch reactor. Isobutylene (33 g) and a similar amount ofisobutane diluent were also charged into the reactor. The mixture wasstirred for two hours, the temperature was increased to 140° C., and thepressure was increased to 580 psi. The conversion, based on the amountof isobutylene starting material, was 85% and the selectivity toisooctene isomers was 62%. The isooctene isomers were separated fromheavier oligomers by atmospheric fractionation. The isooctene isomerswere hydrogenated to isooctane as described in the hydrogenation step inExample 23. The octane value R+M/2 of the hydrogenated isooctane was 98,vapor pressure RVP was 1.65 psig, and freezing point was below −55° C.

Example 41 Isooctene from 1-Butene/Zeolite ZSM-5 Catalyst

A fixed bed continuous flow reactor was loaded with ZSM-5 CBV 2314Zeolite catalyst. Prior to starting the reaction, the catalyst wascalcined at 540° C. under N₂ for 8 hrs. 1-butene was fed into thereactor at a WHSV between 0.2-2.0 h⁻¹ while the reaction conditions weremaintained at 200-240° C. and atmospheric pressure. The 1-butene wasconverted to liquid oligomers at about 80% yield and with a selectivityfor C₄-C₉ isomers of 90%. 1-butene did not oligomerize at thetemperatures at which isobutylene isomers oligomerized, so therelatively high oligomerization temperature range of 200-240° C.produced all of the possible C₄-C₉ olefin isomers, probably due tocracking. Some of the oligomers produced were C₆-C₈ hydrocarbons havinglow levels of branching, and thus had low octane values.

Example 42 Isooctene Hydrogenation

2 grams of 0.5% Palladium on carbon (0.5% Pd/C) catalyst was chargedinto a 2000 mL stainless steel batch reactor equipped with stirrer. 1000mL of a hydrocarbon fraction comprising isooctene isomers was chargedinto the reactor. The reactor was then flushed with nitrogen andpressurized with 100 psig hydrogen. The reaction mixture was stirred forone hour and the temperature was increased from ambient temperature to80-100° C. The reactor was subsequently cooled down to ambienttemperature and excess hydrogen remaining in the reactor was released,and the reactor purged with a small amount of nitrogen. The product wasfiltered off from the catalyst and GC analysis of the product showed100% hydrogenation.

Example 43 Isooctene Alkylate

Oligomerization of more than 95% pure isobutylene with only 5% of otherC₄ isomers (cis and trans 2-butene) over either solid phosphoric acid(SPA) or zeolite ZSM-5 catalysts produced high quality high octaneisooctene isomers. The olefinic product was hydrogenated with hydrogenin the presence of 0.5% Pd/C and gave 100% paraffinic isooctane referredto as “alkylate”. The alkylate produced by this technique comprises morethan 97% of highly branched isooctane isomers, including2,2,4-trimethylpentane (R+M/2=100), 2,3,4-trimethylpentane (R+M/2=98.3),2,2,3-trimethylpentane (R+M/2=104.9), and 2,3,3-trimethylpentane(R+M/2=103). This type of selective oligomerization and the absence ofC₃ and C₅ hydrocarbons in the composition provides an alkylate withsuperior properties (e.g., octane values) compared to the analogouspetroleum refinery alkylate. The minimum octane value of the alkylateprovided by oligomerization of a C₄ olefinic feed is 98, while theaverage octane value of typical petroleum refinery alkylate is 92-94,and this refinery alkylate contains considerable amounts of C₆, C₇, andC₉ isomers.

Example 44 BTEX and Hydrogen from Isobutylene Aromatization

A fixed bed continuous flow reactor was loaded with ZSM-5 CBV 8014Zeolite catalyst. Prior to initiating the reaction, the catalyst wascalcined at 540° C. under N₂ for 8 hrs. Isobutylene was fed into thereactor at a WHSV of 1.0 h⁻¹ while the reaction conditions weremaintained at 400-550° C. and atmospheric pressure. Aromatic productswere formed in about 45% yield with a selectivity for BTEX of 80%. Thearomatic products were isolated and used in fuels and other products.Hydrogen also was produced as a byproduct of the reaction; about 3 molesof hydrogen were produced for each mole of aromatic ring formed.

Example 45 BTEX and Hydrogen from Isobutylene Aromatization

A fixed bed continuous flow reactor was loaded with ZSM-5 CBV 5524 Gzeolite catalyst. Prior to initiating the reaction, the catalyst wascalcined at 540° C. under N₂ for 8 hrs. Isobutylene was fed into thereactor at a WHSV of 1.0 h⁻¹ while the reaction conditions weremaintained at 400-550° C. and atmospheric pressure. Aromatic productswere formed in about 40% yield with a selectivity for BTEX of 80%. Thearomatic products were isolated and used in fuels and other products.Hydrogen also was produced as a byproduct of the reaction; about 3 molesof hydrogen were produced for each mole of aromatic ring formed.

Example 46 BTEX and Hydrogen from Isobutylene Aromatization

A fixed bed continuous flow reactor was loaded with Zeolite type Y CBV780 catalyst. Prior to initiating the reaction, the catalyst wascalcined at 540° C. under N₂ for 8 hrs. Isobutylene was fed into thereactor at a WHSV of 1.0 h⁻¹ while the reaction conditions weremaintained at 400-550° C. and atmospheric pressure. Aromatic productswere formed in about 25% yield and with a selectivity for BTEX of 80%.The aromatic products were isolated and used in fuels and otherproducts. Hydrogen also was produced as a byproduct of the reaction;about 3 moles of hydrogen were produced for each mole of aromatic ringformed.

Example 47 BTEX and Hydrogen from Diisobutylene Aromatization

A fixed bed continuous flow reactor was loaded with ZSM-5 CBV 8014Zeolite catalyst. Prior to initiating the reaction, the catalyst wascalcined, at 540° C. under N₂ for 8 hrs. Isobutylene was fed into thereactor at a WHSV of 1.6 h⁻¹ while the reaction conditions weremaintained at 400-550° C. and atmospheric pressure. Aromatic productswere formed in about 38% yield and with a selectivity for BTEX of 80%.The aromatic products were isolated and used in fuels and otherproducts. Hydrogen also was produced as a byproduct of the reaction;about 3 moles of hydrogen were produced for each mole of aromatic ringformed.

Example 48 Aviation Gasoline

Aviation gasoline (Avgas) blend was prepared by blending hydrocarbonscomprising 90% renewable hydrocarbons. The Avgas blend was formulatedmainly from isooctane, toluene, isobutylene, and isopentane or isomerateblend. Toluene obtained from a BTEX aromatic blend and was used in theAvgas formulation. To meet the Avgas ASTM D-910 standard, the Avgas wasformulated from 70-80% alkylate, 10-20% toluene, 1-3% isobutylene, and10% of a petroleum isomerate stream or isopentane. The motor octanenumber (MON) value for a lean mixture was higher than 100 as requiredfor standard Avgas grades 100LL and 100. The sulfur content was 1-10ppm—substantially below the 500 ppm maximum standard of ASTM D-910. Allother specifications such as freezing point, oxidation stability of thisAvgas met or exceeded the requirements of the D-910.

Example 49 Auto Gasoline

Several formulated auto gasolines (gasoline(s)) were prepared from ablend of 90% renewable and 10% petroleum hydrocarbons. The gasolineblends were formulated mainly from isooctane, isooctene, BTEX,isobutylene, and isopentane or isomerate blends. Benzene from BTEX wasfractionated and removed and it was used for the production of highermolecular weight aromatic molecules (e.g., by alkylation of aromatics asdescribed herein). Gasoline blends were formulated from 50-80%isooctane, 0-10% isooctene, 1-3% isobutylene, 10-20% BTEX, and only 10%of petroleum isomerate blend or isopentane. Because the octane valuesR+M/2 of isooctane and isooctene are above 98, and the BTEX R+M/2 isabove 100, the octane value of the gasoline produced thereby was morethan 100, the sulfur content was only 1-10 ppm, the benzene level wasless than 0.5% and the amount of aromatics was below about 20%. Thisformulated gasoline meets all of the requirements of ASTM 4814(including the RVP value), and is expected to meet gasoline standardsfor 2010 and beyond.

Example 50 Jet Fuel from Isobutylene over Zeolite

The trimerization of isobutylene was carried out using a fixed bedcontinuous flow system equipped with a tube furnace housing SS 316reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, a backpressure regulator, and a gas-liquid separator. In a typicaltrimerization procedure the reactor was loaded with β Zeolite CP 814C(Zeolyst International) and isobutylene was fed into the reactor at aWHSV of 1-3 h⁻¹ while the reaction conditions were maintained at140-180° C. and atmospheric pressure. The isobutylene conversion wasabout 85% with a product distribution of about 29% isobutylene dimerisomers, about 58% of isobutylene trimer isomers, and about 11% ofisobutylene tetramer isomers. The hydrogenation of the resultingoligomer blend was carried out over a 0.5% Pd/Alumina catalyst at 150°C. and 150 psi H₂ to give a mixture which was fractionated to isolate ablend of isobutylene trimers and isobutylene tetramers that were used asa jet fuel feedstock.

Example 51 Jet Fuel from Isobutylene Over Amberlyst® 35

The trimerization of isobutylene was carried out using a fixed bedcontinuous flow system equipped with a tube furnace housing SS 316reactor (OD 5/16 in×12 in), gas flow meters, an HPLC pump, a backpressure regulator, and a gas-liquid separator. In a typicaltrimerization procedure the reactor was loaded with Amberlyst® 35 (Rohmand Haas) and isobutylene was fed into the reactor at a WHSV of 1-3 h⁻¹while the reaction temperature was maintained at 120-140° C. by removingthe heat from the exothermic reaction using a water bath to cool thereactor. The reaction was carried out at atmospheric pressure. Theisobutylene conversion was 95% with product distribution of about 20%isobutylene dimer isomers, about 70% of isobutylene trimer isomers andabout 10% of isobutylene tetramer isomers. The hydrogenation of theresulting oligomer blend was carried out over a 0.5% Pd/Alumina catalystat 150° C. and 150 psi H₂ to give a mixture which was fractionated toisolate a blend of isobutylene trimers and isobutylene tetramers thatwere used as a jet fuel feedstock.

The properties of the jet fuel feedstock produced from isobutylene overan Amberlyst® 35 catalyst, and blends with t-butylbenzene and Jet A-1was compared to the jet fuel specifications of ASTM D1655. As shown inthe Table 2, the jet fuel feedstock itself meets or exceeds all ASTMD1655 specifications except for the density and API gravity (the lowdensity is due to the lack of aromatic compounds). Blends with 12 vol %t-butylbenzene show that the addition of one type of aromatic compoundwill bring the density and API gravity parameters within the ASTMspecification. In addition, the jet fuel feedstock can be blended up to58 vol. % with conventional petroleum derived Jet A-1.

TABLE 2 Comparison of Example 51 Jet Fuel Feedstock/Blends with ASTM D1655 Renewable jet Renewable Jet Jet A or Renewable Fuel Feedstock FuelFeedstock ASTM Jet A-1 Jet Fuel plus 12 v % plus 42 v % Property methodASTM D 1655 Feedstock t-Butylbenzene Jet A-1 Appearance Visualappearance visual Clear, bright Clear, bright Clear, bright and visuallyand visually and visually free from free from free from solid mattersolid matter solid matter and undissolved and undissolved andundissolved water at ambient water at ambient water at ambienttemperature temperature temperature Saybolt Color D156 report +30Composition 1. Aromatics, vol % D1319 25 max <1 13 8.4 Olefins, vol %D1319 <1 2 1 Sulfur, total mass % D1266 0.30 max 0.01 0.02 0.01Volatility Distillation D86 Temperature, ° C. IBP 168 172 177 10%recovered 205 max 178 178 185 20% recovered 181 180 188 50% recoveredreport 190 186 195 90% recovered report 250 244 238 FBP 300 max 305 290284 Distillation residue, % 1.5 max 0.5 1 1 Distillation loss, % 1.5 max0.5 0.5 0.5 Flash Point, ° C. D3828 38 min 49 48 50 Density at 15° C.,kg/L D1298 0.775-0.840 0.768 0.782 0.778 API gravity at 60, ° F. D129853 49 50 Fluidity Freezing Point, ° C. D2386 40 for Jet A −80 −80 −70 47for Jet A-1 Viscosity at −20° C., cSt D445 8 max 7 6 5 Combustion Netheat of combustion, MJ/kg D3338, 42.8 min 43.9 42.6 43.1 Hydrogencontent, mass % D3343 15.08 14.30 14.51 Smoke point, mm or D1322, 25 minSmoke point, mm and D1322, 18 min, 28 28 28 naphthalene, vol % D1840 3.0max Corrosion Copper strip, 2 h at 100 ° C. D130 No 1 max 1b 1b 1bThermal stability Filter pressure drop, mm Hg D3241 25 max 1 1 1 tubevisual rating 3 max <1 <1 <1 Contaminants Existing gums, mg/100 mL D3817 max 2.5 3.2 4.2 Water reaction interface D1094 1 b rating Waterseparation index, D3948 85 min 98 98 98 microseparometer rating (with ECadditive) 70 min (without EC additive) Lubricity (BOCLE) D5001 0.8500.825 0.800 Wear scar diameter, mm Electrical conductivity, pS/M D2624600 max 2 3 3

Example 52 Integrated Oligomers Production

Isobutanol produced by fermentation (e.g., as described in Example 1)was separated from the fermentation broth by distillation. Theisobutanol, which contains 16% water, was passed through a chemicalreactor containing pelleted SPA catalyst heated to 350° C. at 1atmosphere. Water was drained from the bottom of the reactor andisobutylene was collected with 99% conversion. The isobutylene gas wasdried by passing it through molecular sieves, and was then fed into asecond reactor containing Amberlyst® 35 (Rohm and Haas) catalystmaintained at 120-140° C. and ambient pressure to give 90% conversion toa mixture of about 27% of diisobutylene isomers and about 70%triisobutylene isomers, and minor quantities of higher molecular weightproducts.

Example 53 Integrated Saturated Oligomers Production

Isobutanol produced by fermentation was separated from the fermentationbroth by distillation. The isobutanol, which contains 16% water, waspassed through a chemical reactor containing pelleted SPA catalystheated to 350° C. at 1 atmosphere. Water was drained from the bottom ofthe reactor and isobutylene was collected with 99% conversion. Theisobutylene gas was dried by passing it through molecular sieves, andthen fed into a second reactor containing Amberlyst® 35 (Rohm and Haas)catalyst maintained at 120-140° C. and ambient pressure to give 90%conversion to a mixture of about 27% of diisobutylene isomers and about70% triisobutylene isomers and minor quantities of higher molecularweight products. This oligomers blend was then fed into a third reactorto hydrogenate the olefins over 0.5 Pd supported in alumina at 150° C.and 150 psi H₂. The resulting product was fractionated to isolate ablend of isobutylene trimers and tetramers that were used as a jet fuelfeedstock.

Example 54 Benzene Alkylation with Isobutylene over Beta Zeolite

Benzene was alkylated with isobutylene in batch-type reactor. Thereactor was loaded with 1.25 g of Beta Zeolite CP 814E (ZeolystInternational) and 55.5 mL (48.75 g) of benzene, sealed into thereactor, and the reactor was then purged with nitrogen. 11.4 g ofisobutylene were then loaded into the reactor and the reactor waspressurized with N₂ to 500 psi. The reaction was carried out at 180° C.for 2 hours. The reactor was then cooled to room temperature,depressurized and the liquid product was analyzed by GC. t-Butylbenzenewas produced in 38% yield.

Example 55 Hydrogenation Using H₂ from BTEX Process

The hydrogenation of an oligomer blend is carried out over a 0.5%Pd/Alumina catalyst at 150° C. with 150 psi of H₂ obtained from the BTEXprocess.

Example 58 Terephthalic Acid from Xylene

A round bottom flask equipped with a stirring mechanism, Dean-Starktrap, and outlet to a gas bubbler was charged with 0.024 mol p-xylene,0.83 mol glacial acetic acid, 0.009 mol bromoacetic acid, and 0.021 molcobalt acetate tetrahydrate. The contents were heated to reflux asoxygen at the rate of 20 g/h was passed through the mixture for 2 h.Water formed during the oxidation of p-xylene was collected in theDean-Stark trap. After the reaction mixture was cooled to roomtemperature, terephthalic acid was filtered from solution, washed withfresh glacial acetic acid, and air dried. A yield of 75% terephthalicacid was obtained.

1. A process for preparing renewable hydrocarbons comprising: (a)treating biomass to form a feedstock; (b) fermenting the feedstock withone or more species of microorganism, thereby forming isobutanol; (c)dehydrating at least a portion of the isobutanol obtained in step (b),thereby forming a product comprising one or more C₄ olefins; (d)isolating the one or more C₄ olefins; (e) oligomerizing at least aportion of the one or more C₄ olefins isolated in step (d), therebyforming a product comprising one or more C₈-C₂₄ unsaturated oligomers;and (f) hydrogenating at least a portion of the product of step (e) inthe presence of hydrogen, thereby forming a product comprising one ormore C₈-C₂₄ saturated alkanes; whereby the product of step (f) itselfmeets the requirements of at least one of ASTM D4814, ASTM D975, ASTMD910, or ASTM D1655, or a blend of at least 10% of the product of step(f) with a mixture of hydrocarbons meets the requirements of at leastone of ASTM D4814, ASTM D975, ASTM D910 or ASTM D1655.
 2. The process ofclaim 1, wherein said dehydrating, oligomerizing, and hydrogenating areeach carried out in the presence of a dehydration catalyst,oligomerization catalyst, and a hydrogenation catalyst, respectively. 3.The process of claim 2, wherein each of said dehydrating, oligomerizing,and hydrogenating are carried out in a different reaction zone.
 4. Theprocess of claim 2, wherein two or more of said dehydrating,oligomerizing, and hydrogenating are carried out in the same reactionzone.
 5. The process of claim 2, wherein one or more of the dehydrationcatalyst, oligomerization catalyst, or hydrogenation catalyst areheterogeneous catalysts.
 6. The process of claim 2, wherein one or moreof the dehydration catalyst, oligomerization catalyst, or hydrogenationcatalyst are homogeneous catalysts.
 7. The process of claim 1, whereinsaid dehydrating and/or said oligomerizing are carried out in thepresence of an acidic catalyst, wherein the acidic catalyst fordehydrating and the acidic catalyst for oligomerizing is the same ordifferent.
 8. The process of claim 7, wherein said acidic catalyst fordehydrating and said acidic catalyst for oligomerizing are eachindependently selected from the group consisting of inorganic acids,organic sulfonic acids, alumina, neutral chromium treated alumina, acidtreated aluminum oxide, zeolites, solid phosphoric acid,heteropolyacids, perfluoroalkyl sulfonic acids, metal salts thereof,mixtures of metal salts, and combinations thereof.
 9. The process ofclaim 1, wherein said hydrogenating is carried out in the presence of ahydrogenation catalyst selected from the group consisting of copper,chromium, molybdenum, iridium, palladium, rhodium, nickel, ruthenium,platinum, rhenium; compounds thereof; Raney catalysts; and combinationsthereof.
 10. The process of claim 1, further comprising removing saidisobutanol from the feedstock before said dehydrating.
 11. The processof claim 10, wherein said removing comprises carrying out saidfermenting in step (b) below atmospheric pressure, whereby aqueousisobutanol vapor is removed.
 12. A process of preparing a renewablegasoline comprising the method of claim 1, whereby the product of step(f) itself meets the requirements of ASTM D4814, or a blend of at least10% of the product of step (f) with a mixture of hydrocarbons meets therequirements of ASTM D4814.
 13. A process of preparing a renewablediesel fuel comprising the method of claim 1, whereby the product ofstep (f) itself meets the requirements of ASTM D975, or a blend of atleast 10% of the product of step (f) with a mixture of hydrocarbonsmeets the requirements of ASTM D975.
 14. A process of preparing arenewable jet fuel comprising the method of claim 1, whereby the productof step (f) itself meets the requirements of ASTM D1655, or a blend ofat least 10% of the product of step (f) with a mixture of hydrocarbonsmeets the requirements of ASTM D1655.
 15. A biofuel or biofuelprecursor, prepared by the process of claim
 1. 16. The biofuel orbiofuel precursor of claim 15, wherein the product of step (f) is atransportation fuel meeting the requirements of ASTM D4814, D975, D910,or D1655.
 17. The biofuel or biofuel precursor of claim 15, wherein theproduct of step (e) comprises primarily butene dimers and/or butenetrimers.
 18. A biofuel meeting the requirements of D4814, D975, D910, orD1655, prepared by blending the biofuel or biofuel precursor of claim 15with a petroleum-derived hydrocarbon.
 19. A process of preparing arenewable aviation gasoline comprising the method of claim 1, wherebythe product of step (f) itself meets the requirements of ASTM D910, or ablend of at least 10% of the product of step (f) with a mixture ofhydrocarbons meets the requirements of ASTM D910.
 20. The process ofclaim 1, wherein dehydrating step (c) is conducted in the gas phase. 21.The process of claim 1, wherein oligomerization step (e) is conducted inthe liquid phase.